Ball screw pairs of high static stiffness is to guarantee the positioning accuracy and speed of ball screw pair a good ability to adapt the key.Considering the influence of deformation on nut assembly static axial stiffness nut bearing radial,based on simplified model on the analysis of simplified nut assembly static axial stiffness calculation formula.Through the example,will consider the simplified calculation of the pair radial deformation and the traditional ball screw calculation results and the experimental test results for comparison,proved that does not consider the effect of deformation on the ball screw pairs nut assembly static axial stiffness nut bearing radial calculation to the static stiffness is not comprehensive.The research results laid a foundation for the accurate analysis and optimal design of ball screw.