Abstract: Kinematics theory of a multibody system was used to analyze translational joint error, rotational joint error and quadrature error in the spherical grinding system. This paper proposed a virtual grinding point method based on the feature of the process, and the feasibility as well as effectiveness of this method were also demonstrated. A volumetric error model of the grinding system was built up, and the corresponding value of the geometrical error was measured through a laser interferometer. Finally, a software compensation method was employed to validate the model. The experimental results show that the spherical surface grinding precision is significantly improved by geometrical error compensation.