Abstract: The elastic deformation between the ball and groove affects the ball screw's performance, especially when the ball screw is used for precise transmission.However the effect of the helical angle is neglected in the simplified mechanics model of the ball screw.In this paper, a mechanics model of the ball screw is developed considering the factor of lead angle.And the effect of lead angle on the elastic deformation is analyzed.The result shows that the normal elastic deformation of ball screw decreases with the lead angle.The conclusion is significant for research and the development of new high speed ball screw.