Co-op store, new film blossom in Peking spring.

It is too early for flowers to bloom outdoors, but the past month has been unseasonably mild, and most people have shed the fur hats with flying ear flaps that give winter cyclists a rakish Tibetan or Mongolian air.

Across the vast square in front of the cavernous Peking railway station, the Spring Wind food store does a roaring business in candy, biscuits, cooked meat, orangeade - anything edible a long-distance train traveler may desire.

Unless you are a foreigner or an official - or a friend of the train crew, you will travel by hard seat (or hard berth if you are lucky) - overnight to Shanghai, or two days to Canton, or a week to distant Sinkiang.

A couple of pounds of peanut toffee, a couple of boxes of Peking dried pears, a box or two of biscuits will make good traveling companions and delight your friends at your distant destination. Manager Wang Yumei keeps her store open 24 hours a day. Her 150 white-jacketed employees, almost all girls in their teens or twenties, work eight-hour shifts.

''We have to be ready whenever a customer walks in, even in the wee hours of the morning,'' Mrs. Wang says with a smile.

Spring Wind is a cooperative store, funded by the local neighborhood committee and run by the young staff members themselves. This type of enterprise is becoming increasingly popular in many cities as a means both of relieving urban unemployment and increasing services to a citizenry inured to lackadaisical store clerks treating clients as supplicants.

''We started the store two years ago, with money borrowed from the neighborhood committee,'' Mrs. Wang recalled. ''Last year we grossed 4.2 million yuan (about $2.3 million) and cleared a 180,000 yuan profit. We paid back all the money we borrowed.''

Behind the long counter, girls were busily weighing candy on the scales, taking down carbonated drinks from the shelves, breaking open boxes of dark chocolate.

''I was jobless for half a year after I failed my university entrance examination,'' said deputy manager Ma Huiyun. ''I was very pleased to be given a job when this store was opened in February 1980.''

As deputy manager she makes about 40 yuan (about $22) a month. ''It's much more rewarding than working in a state store. We make our own decisions.''

''Of course,'' interjected Mrs. Wang, ''if we make a wrong decision, we have to bear the financial consequences. But so far we've done very well.''.

Rubik's Cubes have swept China as they have the rest of the world. In Peking alone, 300,000 citizens have purchased what are known here as ''magic cubes.'' A group of waiters crowded around a companion in a restaurant, shrieking with laughter as he failed to line up the yellows. ''You're too old,'' said one, ''you have to be a child to do this thing properly.''

''Xi ying men'' (''Happiness Knocks at the Door'') has won an honorary prize at this year's Golden Cock awards given by China's motion picture association. The movie deals with the comic ups and downs of family life in a farming village.

The Communist Party's propaganda department and the Ministry of Culture have been trying to get screen writers and film directors to take up rural themes, since four-fifths of China's 1 billion people live in the countryside.

But although many films include bucolic shots of young children riding water buffaloes or of fields of ripening grain, somehow the life of ordinary peasants has not been a popular subject for filmmakers.

''Xi ying men,'' written by Xin Xianling and directed by Zhao Huanzhang, is an exception. Handsomely filmed in color by the Shanghai Film Studio, it depicts the daily lives of an extended peasant family. It tells of the complications of parents and in-laws.

All ends happily, but in the process the filmgoer learns a bit about how hard old customs die in the countryside - marriage as a form of bargaining between two families. And there is a new element that increasingly disturbs the authorities - the tendency of younger people not to take as unquestioned good care of their elders as in the old days.

Capitalist tendencies in the countryside may be bothering the authorities also. A farmer in a remote Sichuan county was allowed by his commune to start a brick kiln and to hire workers for it. Soon he branched out into the pickling business, sending jars of homemade fiery Sichuan pickles down the Yangtze to an outlet in faraway Wuhan. In two years he had 8,000 yuan in the bank.

''What are you going to do with all that money?'' a traveler asked him. ''Well,'' said the peasant, ''I'm looking around for some good investment, so that my money will earn more money.''

Then he asked the traveler anxiously, ''Do you think Deng Xiaoping (China's senior leader identified with the new economic incentive policies) will stay in power?''