The joint clearance is an important factor to the parallel robot’s pose precision. The limited error method was adopted in finding the function relationship, distribution graphic of joint clearance and end effector’s pose precision in equivalent model by analytical numerical method. Compared in analysis with the condition number of the robot dynamic Jacobian matric, conclusions are drawn: the position error’s distribution is similar to the cond(J)’s, but the pose error is in opposite. The conclusions can be regard as the theoretical basis for the optimization design of mechanism.