Born in Pingtung, Su was a practicing lawyer (1973-1983) educated in the National Taiwan University. He was a defense lawyer in the Kaohsiung Incident trials. He was previously the magistrate of Pingtung (1989-1994).
His first election as the Taipei magistrate was aided by a split between the New Party and the Kuomintang. His subsequent elections have occured by wide margins despite the ability of the pan-blue coalition to present a united candidate.
Su is married to Chan Hsiu-ling (詹秀齡 Zhān Xìulíng) with three daughters.
See also: Politics of Taiwan