[citation needed] In January 1906 he became supervisor of Imperial Peiyang University, and served until December 1911.

In 1912, after the establishment of the Republic of China, he became director of Zhili Education Bureau, a position at provincial level.

Under the Beiyang government, he served as President of National Peiyang University between February 1913 and March 1914, and then he rose to become Minister of Education.

[1] In 1921 he was appointed general manager of Nanchang–Jiujiang railway, serving in the post until he died in 1923.

[citation needed] Cai has a daughter, Cai Baozhen (蔡葆真), who once served as president of Beijing Children's Library, she was married to Ying Qianli (1900–1969), a prominent Catholic layman and educator.