Provided are a testing system and method for evaluating lead screw prestretching force and dynamic performance of a feeding system. The testing system is provided with a motor arranged on a base, a lead screw connected with the motor through a coupler, a nut arranged on the lead screw, a workbench fixedly connected with the nut through a nut base at the bottom, a laser interference testing system, a modal testing system and a thermal feature testing system. A guide rail is arranged on the base through a guide rail supporting frame. The lead screw is positioned through a front bearing mechanism and a tail bearing mechanism, and the front bearing mechanism and the tail bearing mechanism are fixed to the base. The testing method includes the steps that an elastic shaft sleeve is calibrated through an elastic shaft sleeve calibration device, and a calibrated linear relation expression of the elastic shaft sleeve is obtained; and modal testing, motion performance index testing and thermal feature testing of the feeding system are carried out correspondingly under different axial prestretching forces of different gradients. According to the testing system and method, testing data are processed based on an evaluation index, the rule of influences of the prestretching force of the lead screw to the dynamic performance of the feeding system is analyzed, and the prestretching force state of the lead screw is evaluated comprehensively.