In order to solve the problem that mechanical weighing table is difficult to calibrate due to static instability, we have analyzed the measuring principle and mechanical characteristics of the mechanical weighing table and proposed the calibration method of the mechanical weighing table in this paper. By reducing the maximum deflection angle of the weight frame of the mechanical weighing table under non?equilibrium state, the measurement uncertainty can be controlled during calibration and the accuracy of calibration results can be guaranteed. The method is used to calibrate the mechanical weighing table and analyze the measurement uncertainty. The results show that the extended uncertainty U = 84 g (k = 2), which verifies the effectiveness of the method. The research results have a positive impact on promoting the development of the mechanical metrology of underwater vehicle products, and provide a strong support for the experimental research of underwater vehicle products.