The Political Bureau of the CPC Central Committee is elected by the plenary session of the CPC Central Committee.

The Party's Constitution has stipulated since the 12th National Congress that "a plenary session of the Central Committee is held at least once a year by the Political Bureau of the Central Committee," and that "the Political Bureau of the Central Committee and its Standing Committee exercise the functions and powers of the Central Committee when the plenum of the Central Committee is not in session.

The Political Bureau regularly reports its work to the Central Committee and observes the principle of a collective leadership. The general secretary of the CPC Central Committee is responsible for calling the sessions of the Political Bureau. The Political Bureau must faithfully carry out the Party's policies, principles and guidelines adopted at the National Congress. Its decisions concerning the transfer and reshuffling of personnel within the leading bodies of central organizations and issues of great importance within the Party must be endorsed by the plenary session of the Central Committee.

(From china.org.cn)