Peking — The Chinese Communist Party is taking a hard look at itself - and not always liking what it sees.
That, at least, is the position of China's present leadership, which has made party ''rectification'' a major theme of the 12th party congress, meeting here since Sept. 1.
The leadership has announced a three-year program of party reform - restructuring top party posts and weeding out corrupt officials and ultraleftists who remain from the Mao Tse-tung era.
The reforms are important because, in the final analysis, the ambitious economic development program that is to propel China into the ranks of the world's leading industrialized nations by the end of this century will depend for its success on the quality of the party officials who carry it out. The program will also depend on the degree of support and even of enthusiasm that these officials can evoke from China's one billion people.
''The style of a party in power determines its very survival,'' said Chairman Hu Yaobang in his 34,000-character keynote address to the 1,545 delegates and 145 alternates.
And, as Mr. Hu acknowledged, the party has not yet recovered the prestige it lost during the 10-year turmoil of the Cultural Revolution (1966-76).
''Impurities in ideology, style, and organization still exist within the party, and no fundamental turn for the better has as yet been made in the party style,'' he said.
This is the background against which delegates to the party congress are discussing changes in the party constitution and the three-year program of ''rectification.'' The constitutional changes, discussed by congress spokesman Zhu Muzhi at a press conference here Sept. 6, are expected to help solidify the grip of the present reformist leadership headed by vice-chairman Deng Xiaoping, Chairman Hu, and Premier Zhao Ziyang on the party's administrative machinery
The new constitution will also, in Hu's words, forbid ''all forms of the personality cult'' in an attempt to avoid the kind of blind leader-worship that allowed the late Chairman Mao to embark on the disastrous adventure of the Cultural Revolution.
The office of party chairman, held successively by Mao, by his anointed successor Hua Guofeng, and by Hu, will be abolished and the party's day-to-day affairs will be managed by a secretariat headed by Hu as general secretary. This is the same position that Hu's mentor, Mr. Deng, occupied during the 1950s.
The general secretary will be empowered to call meetings of the Politburo and of its Standing Committee as well as of the Secretariat. Deng and other party elders will retire to a new advisory council to be called the central advisory commission.
Still, as long as Mr. Deng is around, the force of his personality and the nature of his relationship with Hu and Zhao ensure that he will be the indispensible core of the new leadership setup.
Advisory commissions are also being set up at the provincial level so as to make room for a younger, more professionally qualified leadership at this all-important intermediate level.
So far, Deng and his associates have maneuvered skillfully to outflank their conservative opponents and gradually to put in place, with a minimum of open opposition, a reorganized party and government structure that they hope will prove adequate to the task of managing economic modernization.
Hu has appealed for a return to the ''Yenan spirit'' - the spirit of the days when the party was still a guerrilla movement that could survive only by swimming in the ocean of popular support. Both ultraleftism and ''bourgeois liberalism'' will be condemned and, over a three-year period, the credentials of all party members will be reexamined and corrupt or otherwise undesirable elements weeded out.
That is the plan. But can a party actually enjoying all the perquisites of power succeed in reforming itself?
At the end of July, Yang Yibang, one of the deputy ministers of the chemical industry, was stripped of his party posts and placed on two years probation for graft and corruption. Mr. Yang is the highest official to be disciplined so far on this kind of charge.
But he received no jail sentence and the switchboard at the People's Daily was jammed with telephone calls from indignant individuals demanding to know why he had been let off so lightly.
There is a very strong feeling here that the authorities are still merely ''swatting flies while letting the tigers go free.''