The contacts of vacuum circuit breaker often appear fusion in the short-time withstand current and peak withstand current test. The influence of short-time current and peak withstand current on the teat is analyzed. According to the actual situation of the test and the electric contact theory, the contacts temperature under the short-time withstand current and the electric repulsion force between the contacts under the peak withstand current are calculated. The contact force values under different withstand current are given. The electric repulsion force is simulated by the finite element method, which verifies the correctness of using the empirical formula to calculate the contact force.(from magazine Electrotechnical Application5/2020 on theoretical analysis.)