The auxiliary beam provides a solution to enhance the mechanical properties of the connector by modifying the structure of the spring plate. In this paper, an on-board small connector is taken as the research object. Firstly, the mathematical model between the contact normal force and contact deformation of the terminal with rolling tongue cantilever beam structure is constructed, and the size and material parameters of the terminal were substituted to calculate the contact normal force of 0.43N. Then, the insertion and extraction simulation of the connector terminal is carried out with ANSYS simulation software, and the contact normal force is obtained to be about 0.40N, with a relative error of 7.5% compared to the theoretical calculation result. However, the contact normal force does not meet the design requirements. To solve this problem, this paper adds an auxiliary beam between the metal shell of the socket and the main beam of the spring plate, and ANSYS simulation is performed and analyzed. According to the simulation results, the addition of the auxiliary beam increases the contact normal force to 2.66N, and the insertion and extraction force reaches about 1N. The auxiliary beam effectively improves the contact normal force and insertion and extraction force of the connector terminals, but it also poses a potential problem of making the auxiliary beam stress exceed the yield limit of the material.