Informed and vivid look at life in China today

One Billion: A China Chronicle, by Jay and Linda Mathews. New York: Random House. 353 pp. $17.95. Most writers about contemporary China fall into two rough categories. Academics often write complex descriptions based heavily on policies presented in documents or speeches by assorted senior Chinese bureaucrats. These writers typically devote themselves to the endless struggles bureaucrats engage in. The reader is often left to guess what all this means, if anything, to the average Chinese citizen.

Journalists, by contrast, lean toward tales of everyday life, filled with humorous, frightening, zany, or poignant anecdotes. ''One Billion,'' by reporters Jay and Linda Mathews, understandably leans toward the journalistic approach. The results will greatly please that favorite audience of all journalists - the intelligent lay reader.

Jay Mathews was the first Peking bureau chief for the Washington Post; Linda Mathews holds a similar job for the Los Angeles Times. The Mathewses bring solid credentials to their journalistic tasks and to this new book on life in China today. For example, they often cite research that is usually known only to China-scholars. Yet, these findings are frequently tested and humanized by the Mathewses' reporting. For example, American sociologists have argued that most rural Chinese ignore the official policy that demands the cremation of the dead. The Mathewses strengthen this scholarly argument by reporting a black market that arose to smuggle bodies out of cities for a ''proper'' burial in the countryside. They also report that older peasants are reluctant to go to urban hospitals, lest they die and are cremated. We even learn that otherwise-loyal government officials often shrug their shoulders at such inconsistencies. Linda Mathews tells of a talk with the daughter of an ''upstanding party family'' whose grandmother objected to cremation. ''But you cremated her anyway?'' Linda asked. ''No,'' said the woman, ''we buried Grannie just like she told us to.''

The structure of the book is simple and sensible. After a few introductory pages, it moves into descriptions of society - city and country life, the special significance of the Chinese language, sex, marriage, what it's like to be young or old in the ''New China.'' This is followed by a section somewhat ominously called ''The System.'' Fittingly, the section begins with a peasant-style epigram: ''The (Chinese) Nationalists had lots of taxes; the Communist Party has lots of meetings.''

Throughout ''The System'' (and elsewhere, too) we find an essential theme of ''One Billion'' - life in China for almost everyone is an endless duel between Communist Party rules and everyday reality. In the abstract, one agrees that there is a need to limit a massive population that grows at a rate of 15 million a year. Yet limiting population in China can profoundly and repugnantly infringe on the historical desire of families to produce at least one male heir. In fact, much of the book deals with the great struggle to preserve the family (not the rights of the individual as in the West) against the encroachments of the seemingly all-powerful state. The reader comes away with a renewed respect for the dogged tenacity of the family structure.

If ''The System'' is the heart of the book, then the last major section is its soul. Somewhat wryly called ''Escape,'' it tells of the small pleasures that China's citizenry tries to squeeze out of the system. Some battles are won, some lost. Beginning, appropriately, with food (China's obsession), we learn of the arts (Peking opera is another obsession), movies (Charlie Chaplin is popular), music (love ballads from Taiwan sell on a kind of musical black market), fun and games (cricket fights have reemerged), and humor (the great Chinese sense of humor lives on, despite or perhaps because of communism).

''One Billion'' contains an unexpected bonus. The Mathewses were the first American correspondents to have young children in China, and thus the book is sprinkled with striking observations about children that a childless journalist might never have noticed.

China is too important to be left to the specialists. Books such as ''One Billion'' - thoughtful and very well written - deserve a wide audience.