The utility model discloses a device testing the influence of direct current system alternating current cross-talk and voltage fluctuation on a relay. The device comprises an alternating current output circuit, a system capacitor output circuit, and a resistor output circuit. One output terminal of the alternating current output circuit is connected between the relay to be tested and the negative pole of a direct current system, and the other output terminal is grounded. One output terminal of the system capacitor output circuit is connected between the positive pole of the direct current system and the relay to be tested, and the other output terminal is grounded. One output terminal of the resistor output circuit is connected between the relay to be tested and the negative pole of the direct current system, and the other output terminal is grounded. According to the utility model, under various faults of alternating current and direct current cross-talk, direct current system voltage fluctuation and the like, a protection device is visually and accurately researched; the test device is used to test different models of relays to be tested; according to test data, the influence of different insulation states on a relay protection characteristic can be visually and accurately analyzed; the safety of system operation is improved; improvement suggestions are provided for the existing insulation monitoring device; and the reliability of power grid operation is improved.