Cofounded Chinese Communist Party (CCP) with Chen Duxiu in 1921. Worked as a librarian at the Beijing University Library and was among the first of the Chinese intellectuals who supported the Bolshevik government in the USSR. Mao Zedong was an assistant librarian during Li's tenure at the library and Li was one of Mao's earliest and most prominent influences. By many accounts, Li was a nationalist and believed that the peasantry in China were to play an important role in China's revolution.
Under the leadership of Li and Chen, the CCP developed a close relationship with the Comintern. The Comintern's directives to the CCP were provided by the Comintern's representative in China, Henk Sneevliet. At the direction of the Comintern, Li and Chen were inducted into Sun Yat-sen's Guomindang Party in 1922. Li was elected to the Guomindang's Central Executive Committee in 1924. The CCP's relationship with the Guomindang was controversial, particularly to many members of the CCP and the relationship gradually deteriorated.
Tensions between the Comintern, the Guomindang, and the CCP presented opportunities for political intrigue and opportunism. As part of Chiang Kai-shek's early efforts to liquidate communists, mass detentions of suspected communists began in early 1927. During the during a raid on the Soviet embassy in Canton, Li was captured and, with nineteen others, he was executed on the orders of the Manchurian general Zhang Zuolin in April 1927.