The invention discloses an inrush current suppression device suitable for testing transformer frequent no-load input. The device is completely serially connected into a power supply loop, the protection and operation method of the original power supply and distribution system will not be changed, so advantages of simple transformation and convenient operation can be realized; and the control circuit is composed of a time relay and a contactor, so advantages of simple structure and no complex digital control can be realized, and the time of the time relay can be adjusted according to actual needs to satisfy the transformer soft starting requirements of different rated capacities and currents, so the device has advantages of broad applicability and wide application range, and play an important support and guarantee in the test of the whole high-power power electronic equipment.