Abstract: Detecting locations of contacts is the most important issue for contact analysis of a joint in multibody dynamics, which traditionally requires the details of the relative motion of bodies in the joint as well as the solution of the resulted complementarity problem. However, clearances in a joint may be so tiny that it is hard to distinguish the relative displacements from computational errors. In this case, the contact analysis becomes extremely difficult due to the serious numerical ill-conditioned characteristics of traditional methods. In this paper, with the consideration of the structural details of deep groove ball bearing, we found the kinematic conditions for a ball to be simultaneously in contact with the inner and outer races, as well as the characteristic of contact forces on the ball that is carrying a load. Consequently, we present a methodology, in which the forces and locations of contacts can be obtained by means of joint reaction forces instead of relative motions. By the proposed method, the difficulties arising from microscopic relative motions and nonlinear complementarity problems are avoided, and the numerical efficiency is improved. Numerical examples prove the validity of the method.