Workpiece localization has direct relations with many manufacturing automation applications. In order to gain accurate workpiece measurement by coordinate measuring machines (CMM) or on-machine measurement system, the touch trigger probe is widely adopted. In spite of the high repeatability of the touch trigger probe, there are still error sources associated with the probe. In this paper, we will focus on probe radius compensation. Several compensation methods in related papers are reviewed. In addition, a new radius compensation method is proposed in this paper. Simulation and experimental results of probe radius compensation by different methods are given. It is shown that our proposed method has the best performance both in terms of compensation accuracy and computational time. The method is also implemented in a computer aided setup (CAS) system.