The present invention discloses a switching-on and switching-off delay setting calculation method capable of restraining converter transformer magnetizing inrush current. The method comprises the following steps: testing switching-off times and switching-on times of a circuit breaker; determining target switching-on angles of the circuit breaker; calculating delay switching-on angles; and calculating switching-off target angles of the circuit breaker. According to the method, each phase of a converter transformer can be switched on at an optimal angle to minimize the generated magnetizing inrush current, each phase of the converter transformer can be switched off at the optimal angle to minimize the generated converter transformer remnant magnetism, and the magnetizing inrush current can be reduced again in the next charging.