The invention discloses a DC power supply system ground fault detector test bed, which is characterized by comprising a first adjustable DC power supply, a second adjustable DC power supply, a positive resistance to ground rotation switch, a negative resistance to ground rotation switch, a positive capacitance to ground rotation switch, a negative capacitance to ground rotation switch, a voltage regulator, a DC mutual-shifting switch, an AC shifting-in switch, resistors R1 to R10, resistors R11 to R20, capacitors C1 to C10, capacitors C11 to C20, a total voltmeter, a positive ground voltmeter and a negative ground voltmeter. The operation is simple and can be adjusted according to the local condition, and problems that the DC power supply system grounding fault detector is difficult in detection, incomplete in detection and little in information can be solved.