The utility model provides a device testing response characteristic of a metal oxide sample under steep-wave-front pulses. The device comprises a steep-wave-front pulse generating unit for generating steep-wave-front current waveform and a tester for testing current and voltage waveforms of the tested sample. The sample is connected into a loop formed by the steep-wave-front pulse generating unit, and two capacitors in the steep-wave-front pulse generating unit are charged by a dc power supply to breakdown a tri-electrode switch, thereby testing the response characteristic of the metal oxide sample under steep-wave-front pulses. The testing device employs a structure which integrates the capacitors with the switch, thereby reducing inductance of the loop; and a mechanism in which copper strips wrap the capacitors tightly is employed, so that inductance in the loop is decreased to the minimum; thus, enough current amplitude and steep rising waves are ensured, and residual voltage of a valve block under steep waves is obviously improved with the increase of steep-wave-front current.