The invention discloses a grounding precision judgment testing system, and the system comprises a computer, a computer display, a first communication circuit, a second communication circuit, a first controller, a second controller, a power switch, an isolation transformer, a first integrated measuring instrument, a second integrated measuring instrument, a circuit breaker upper interface, a circuit breaker lower interface, a simulation arc suppression coil, a first simulation grounding circuit, a first simulation load circuit, a first simulation grounding capacitor circuit, a first simulation arc light grounding circuit, a first variable frequency motor, a first harmonic generator, a second simulation grounding circuit, a second simulation load circuit, a second simulation grounding capacitor circuit, a second simulation arc light grounding circuit, a second variable frequency motor, a second harmonic generator, a first group of current transformers, a second groups of current transformer, a first busbar and a second busbar. The system simulates various grounding systems of a 10kV power distribution system, and achieves the testing of the performance of a grounding precision judgment device.