After the founding of the People's Republic, Su became an admiral in the People's Liberation Army Navy, the Party Secretary of Guizhou province, the First Secretary of Shanghai, and a member of the Politburo of the Chinese Communist Party.

Su joined a guerrilla fighting force in 1926 at age 14, and entered the Communist Youth League three years later.

During the Cultural Revolution, Su was purged and called "a time bomb in the navy planted by Deng Xiaoping."

Su played a pivotal role during the arrest of the Gang of Four in 1976, when he was commissioned by Hua Guofeng and Ye Jianying to 'invade' the Xinhua News Agency, central television and radio stations, and the People's Daily headquarters, which were all then under the control of elements friendly to the Gang of Four.

In order to prevent a coup by the Gang of Four in their power base of Shanghai, Su was then sent to Shanghai as First Secretary to oversee the party organization in collaboration with Ni Zhifu and Peng Chong.