Abstract: Taking the double-nut washer pre-tightened ball screw as the research object, a static contact stiffness model of the double-nut washer pre-tightened ball screw that can consider the non-uniform load distribution is established, and the validity of the model is verified by experiments. The established model can be based on the screw or nut raceway as the analysis object, focusing on the impact of different axial load directions and magnitudes on the contact angle and normal contact force unevenness between the ball and the raceway at all phase angles, and the contact Influence of uneven distribution of angular and normal contact force on static stiffness of axial contact, and the following conclusions are obtained: mainly affected by the uneven distribution of the contact angle, the static stiffness of the axial contact when the screw raceway is used as the analysis object and the axial load is negative; it is mainly affected by the uneven distribution of the normal contact force As the axial load increases, the static axial contact stiffness value obtained without considering the load non-uniformity model will gradually deviate from the axial contact static stiffness value obtained by the load non-uniformity model.