Results of the QCICD/6-311++G(3df,3pd) ab initio calculations on the ground state of Ar2H+ are presented. With accurate method and basis sets, the potential energy surface for the ground state was scanned with more than 7000 points, and an analytic global potential energy surface was constructed based on these points. The properties such as the potential minima, the transition state, and the dissociating paths of [Ar-H-Ar](+) were discussed. The influence of the three-body interaction in this system was also investigated, and it is found that a potential based on the two-body additive interaction is not good to represent the Ar2H+ system.