Leung was educated at the Clementi Secondary School. Leung credits his political awakening to the Cultural Revolution and the 1967 Hong Kong riots, participating in the "Maoist student movement". He and his mother were members of the Hong Kong Federation of Trade Unions (HKFTU), the left-wing pro-communist labour union at the time. After the falls of Lin Biao and the Gang of Four which crushed the Maoist idealism, Leung reflected his political belief, and delved himself into Trotskyism under the influence of the social activist icons at that time such as Ng Chung-yin.