Abstract: In this paper, COMSOL multiphysics analysis software was used to simulate the propagation process of longitudinal waves in the bolt pretightening force detection, and the influence law of stress on the propagation time of longitudinal waves was summarized. Based on theoretical and simulated analysis, the preload test of high strength bearing bolt was carried out. The results showed that when the longitudinal wave excitation signal left the end of the bolt, there was no reflection interference phenomenon. When the wave front propagated to the sudden change of the structure, the wave mode conversion occurred, and the edge shear wave was generated, and the edge longitudinal wave was formed at the bolt side wall. The linear relationship between the pre-tightening force and the acoustic time difference was determined by the simulation and calibration test, and the test data was fitted by the least square method. The overall error is 2. 78% as compared with the tensile machine value.