After some hesitation, most major American news organizations have decided to risk massive confusion and switch to Peking's new official Roman letter spelling system for Chinese names and places.

Amateur Chinawatchers familiar with the well-publicized comings and goings of Chinese Vice Premier Teng Hsiao-ping must now be reintroduced to the same fellow, this time with his name spelled Deng Xiaoping. That beautiful lakeside city, Hangchow, visited by President Nixon in 1972, will now be spelled Hangzhou. Devotees of the Chinese defense minister, Hsu Hsiang-chien, should be forgiven if they do not immediately recognize him with his new identification, Xu Xiangquan.

Peking's decision to standardize its new spelling system represents part of a colossal scheme eventually to convert the Chinese written language, now requiring a minimum of about 5,000 different ideographs, or characters, to a Roman alphabet. Chinese in its present form is one of the world's most beautiful and most inefficient written languages. It has too many different characters to make possible so far an efficient typewriter or speedy telegraphic communication.

Even if the Chinese never eliminate characters, as many purists argue they should not do, the new Roman spelling system first introduced 20 years ago does help standardize the spoken Peking dialect throught the country. Ti also may help foreitners pronounce Chinese words more correctly, if their eyes do not already glaze over at the first signt of a difficult Chinese name.

The Chinese government began using the new system Jan. 1 in all its foreign language publications, including the English-language service of the New China News Agency. This is an important source for American journalists writing about China. The United Nations and U.S. government agencies have adopted the new spellings called by the Chinese "Pinyin" meaning "phonetic spelling."

The Washington Post, the New York Times and some other major American newspapers are scheduled to begin using the new spellings Monday. The Associated Press and UPI also converted this weekend, long after the major Europeann agencies, Reuter and Agence Franco-Presse, had switched.

Some of these organizations, including The Post, have decided to preserve the old spellings for famous deceased Chinese, such as chairman Mao Tse-tung, whose name would be Mao Zedong in the new system, and premier Chou En-lai (Zhou Enlai).

The Post will also retain the old spellings of four familiar place names. They are (with what would have been their new spellings in parenthesis): Peking (Beijing), Canton (Guangzhou), Tivet (Xizang) and Inner Mongolia (Nei Monggol). China's own English language service continues to use the name "China," which under the new spellin would have been rendered "Zhongguo."

Most publications; including The Post, plan to put the old spellings of familiar names and places in parentheses after the new spellings until readers become accustomed to the change. Some publications, such as the Los Angeles Times, plan to use even the new spelling for the Chinese capital, Beijing, instead of Peking. Most organizations will continue to use old spellings for Chinese people and places outside the People's Republic of china, such as Hong Kong, Singapore, Chiang Ching-kuo (Taiwan's president) and Fu Man-chu.

The old spelling system, named the Wade-Giles system after the two 19th century Britons who developed it, made correct pronunciation unnecessarily difficult. It used apostrophes to distinguish aspirated consonants, such as p'ai pronounced with a "p" sound, from unaspirated, such as pai pronounced with a "b" sound. The new Pinyin system eliminates this distinction, which most newspapers ignored anyway. "Beijing" is much closer to the Chinese pronunciation that "Peking", and Vice Premier "Deng" is better rendering than "Teng." But the new system uses some letters in ways that still confuse English speakers. Thers difficult letters are: "c" which should be prounced in this system like the "ts" in "its"; "q" which should be pronounced like the "ch" in "cheek"; "x" which should be pronounced like the "sh" in "she"; and "zh" which should be pronounced like the "j" in "jump".

The system invented by Sir Thomas Wade, diplomat and Cambridge University professor, about 1860 and developed by Herbert Giles, also a Cambridge professor, is only the best known of several in use over the past 100 years. Some of the most familiar Chinese place names, such as Peking and Canton, are derived only partially, or not at all, from Wade-Giles.

Many Chinese fear that whatever Roman letter system the Peking government adopts, using it to replace the current writing system, would cut future agenerations off from more than 2,000 years of some of the finest literature in human history. Computer experts are seeking ways to harness modern electronics so that the ancient complex cnaracters can be transmitted as swiftly as letters in the alphabet. Automatic readers may be able to turn the characters into fourdigit codes that can be transmitted swiftly.

Reading the alphabetized words still presents problems for the Chinese, however, because the spellings do not distinguish the flur separate tones in the Chinese language that can significantly change meaning. The word "ma" can mean "mother", "horse", or "scold", depending on what tone is used. Under the Pinyin system, two neighboring provinces of northern China are both spelled "Shanxi". In this special case, one of the provinces is now spelled "Shaanzi", to indicate a different tone in the first syllable.