Li accepted Christ at the age of 14 when he was studying at a Christian school in Singapore. In 1892, he went to the United States to study and graduated with a bachelor's degree from Yale University (1899). He knew many different languages. In 1901, he began to build schools in Batavia and then went to Shanghai in 1905. He initiated the To Use Education to Arouse the Nation program and the World Chinese Students Federation, which began by encouraging students to be patriotic. He motivated students to boycott American goods when the United States passed legislation prohibiting Chinese laborers.
In 1906, Li taught German and Latin in Fudan Public School and later served there as dean of students. In 1912, he became head of the English department of Zhonghua Publishing House. He became principal of Fudan that year as well. In 1917, when Fudan became a university, Li went to Nanyang twice to raise fund. On his return he improved the school facilities and also began to accept female students. He contributed greatly to the development of Fudan.
During the war of resistance against Japan, Fudan moved. Li remained in Shanghai to set up Shiyan Secondary School. Li loved his country and loved teaching. During the Washington Peace Conference in 1921, he set up the National Peoples' Diplomatic Support Committee to fight against all the powers that were infringing upon China's rights. Li was also a committee member and vice-chairman of the Education Association of the Chinese Protestant Church and the Association of the All China Protestant Church. In 1931, he served as chairman of the Christian Flood Relief Committee. When he became chairman of the Chinese People's Committee Against Opium in 1935, he wrote about and exposed the illegal dealings of public officials, Li was also chosen to be a member of the United States Geographical Society.