公民力量
He was a member of the Hong Kong Affairs Society, a pro-democratic political group in the 1980s, later turned into the first major pro-democratic party United Democrats of Hong Kong (UDHK). Choy was the founding member of the UDHK but soon later he and Lau Kong-wah quit the party and form a local community organisation Civil Force. He was elected as member of the Legislative Council in Election Committee in the 1995 Legislative Council election in which the electorates were composed of district councillors. He later joined the pro-Beijing pro-business Hong Kong Progressive Alliance (HKPA) and reelected to the Provisional Legislative Council in 1996. In the 2000 Legislative Council election, HKPA supported Choy Kan-pui and Tang Siu-tong to participate in the New Territories East and New Territories West constituencies respectively but Choy failed to go back to the LegCo.