On your second trip to China, venture off the beaten path to places like Gongxian and Qufu

The Great Wall at Badaling, outside Peking, is splendid. But if you really want to experience the wall's enormous length, to relive the centuries through which it has stood guard against the northern barbarians, go to Jiayuguan, some thousand miles westward on the old silk road from China to Persia and Byzantium.

The life-size terra-cotta army of Qin Shihuangdi, the first emperor of China, is breathtaking. But you might also like to savor a more intimate sense of the splendor and culture of the China of 2,000 years ago by viewing the miniature terra-cotta army in the museum at Xianyang, which is near Xian and which was Shihuangdi's capital.

By all means visit the Ming Tombs on your way to Badaling. But go see the smaller, more charming Sung Tombs standing in the fields outside Gongxian, near Luoyang.

Jiayuguan takes a bit of planning to get to. You would want to combine it with a trip to Dunhuang, which is also on the old silk road and which has one of the world's greatest surviving art treasures - the sculptures and paintings of the caves of Mogao, dating nearly a thousand years from the northern Wei Dynasty (386-534) to the Mongol Yuan Dynasty (1206-1368).

But Xianyang and Gongxian are both quite accessible. I remember catching my breath over a seated bronze Buddha in the courtyard of the museum in Xianyang, with no explanation other than that it dated from the early Ming Dynasty (1368- 1644). To me, it seemed as serene and otherworldly as the great Buddha of Kamakura, Japan, which is about a century earlier.

That, though, is one of the pleasures of a leisurely excursion to China. Once you have ''done'' Peking and Shanghai, Suzhou, Hangzhou, and Guilin, you should come back for a second or a third visit, to break up your China experience into manageable segments so as not to ingest more than you can absorb.

An expedition to Gongxian opens up all sorts of unexpected delights, from the stone elephants, lions, tigers, sheep, and officials lining the ''sacred way'' leading to each tomb, to the northern Wei cave sculptures along the northern bank of the Luo River. The ''sacred way'' has long since been turned into plowed fields worked by peasants with hoe or ox or hand-held tractor. But the statues stand sentinel, mute testimony to the coexistence of centuries in this timeless land.

Unless you are with a large tourist group, your car with the inevitable China travel service guide will be the only intruder in a landscape of straw-hatted peasant and waving barley. The Wei caves must be approached by Jeep, which the travel service will provide, because for much of the way the road is little more than a track.

Northern Wei is the dynasty that accounts for China's first great age of stone sculptures, mostly of Buddhas, bodhisattvas, and apsaras, with idealized features and archaic smiles reminiscent of the Greek kingdoms of Central Asia. Northern Wei's greatest artistic achievements are the Yungang Caves, near Datong , and the Longmen Caves, outside Luoyang.

The caves near Gongxian are much smaller than either of these. They were hollowed out on a hillside overlooking the Luo between AD 517 and 534. The compound surrounding the caves is adjoined by a primary school, and the curator of the caves makes his detailed explanations of the history and characteristics of the Buddhist statues against a continuous background from across the wall of pupils reciting their lessons in high-pitched Chinese tones.

''All of China is an archaeological site,'' the writer Wang Meng once told me , and indeed there is hardly a square inch of field or forest where a peasant could not dig and find treasured relics of four hundred, seven hundred, or a couple of thousand years ago.

The area surrounding Gongxian is one of the oldest continuously inhabited regions of China, and people are discovering new caves or new tombs all the time. A Han Dynasty (BC 206-AD 220) tomb we visited on the way to Gongxian, had stone carvings of musicians playing the lute, of pigs being roasted whole in the kitchen courtyard, of peasants leading their oxen to the fields - activities that could easily be taking place today.

If caves and tombs are not your cup of tea, however, I would recommend an overnight visit to Qufu in Shandong, which you could combine with an expedition to Mt. Tai, the greatest of China's sacred mountains. Mt. Tai is only 8,000 feet high and can be climbed in a day. Its slopes are covered with temples in varying states of repair, and a pilgrim's greatest ambition is to greet the morning sun from the mountain's peak.

Being a plainsman myself, I prefer the charming town of Qufu, which is just one stop beyond the mountain and where you can spend a lazy afternoon pedaling on a rented bicycle through quiet streets or walking through the forest where Confucius and his descendants the Kong Dukes have their graves.

In Qufu you can stay in a hotel that is part of the now dilapidated but palatial sweeping-roofed pavilions that were the residences of the Kongs.

Your bed may be hard and your bathroom leaky, but open the window of your bedroom and revel in the vista of soaring eaves and blue sky and a moon gate leading into your courtyard.

A little imagination goes a long way.

Practical information:

To reach Jiayuguan: fly from Peking to Lanzhou, then change to a small plane for the flight between Lanzhou to Jiuquan. (This plane frequently fails to fly, because of weather and other conditions.)

Alternatively, there is the train from Lanzhou to Jiuquan. The ride takes you past a string of oases along the old silk road and takes 24 hours.

China Travel Service guides will meet you either at the train station or the airport and escort you to a barely adequate hotel.

From Jiuquan, you can reach Jiayuguan in about half an hour by car, rented from the China Travel Service. Local buses are also available, but Chinese language ability is a must.

From Jiuquan you may also hire a car for Dunhuang, a trip that will take most of the day along the old silk road, or you may join a tour bus operated by China Travel Service.

The Qufu Hotel is operated by China Travel Service, whose representative will meet your train at Yanzhou, the railway town about 12 miles from Qufu.

The overseas arm of CTS, the China International Travel Service (CITS) will provide you with a list of agents that will make these arrangements. Write to it at 60 East 42nd Street, Suite 465, New York N.Y. 10165. Phone (212) 867-0271. According to CITS, Americans traveling independently to China must go in the off-season (late November until March).