Due to its unique advantages such as driving comfort, shock absorption, noise reduction, and convenient management and maintenance, Asphalt Plug Joint has been rapidly developed and applied. However, subject to the long-term coupling action of traffic loads and environmental factors, the Asphalt Plug Joint is prone to interface effects and stress concentration resulting in damage, especially the stress concentration at the contact part between the expansion joint and the steel cover plate is more prominent. The interface between the bridge expansion joint and the pavement, as well as the interface between the bridge expansion joint and the edge of the spanning slab, is prone to stress concentration. To solve the above problems, proposed an improved design scheme of the Asphalt Plug Joint: (1) The bonding performance of the interface has a great impact on the service life of the expansion joint. Therefore, through the pull-off and oblique shear tests, the binder with good bonding performance is selected, and the test data is introduced into the cohesion model to simulate the interface contact. (2) Through the finite element simulation analysis, the main parameters of the Asphalt Plug Joint, such as friction coefficient and the cross section form of the cross-seam plate, are analyzed. The results show that the reasonable use of binder can effectively improve the bonding performance of asphalt binder interface; The debonding of the steel cover plate and asphalt mixture and the easing of the cross section form of the joint slab edge can better adapt to the stress caused by the bridge vehicle and temperature load. The optimization of the geometric design of the steel cover plate has a significant effect on improving the mechanical performance of the Asphalt Plug Joint, and has an important reference value for improving its service performance and extending its service life.