The utility model discloses a vehicle-mounted intelligent grounding detection system. The detection system comprises a signal collection module, a simulation signal processing module, an analog-to-digital conversion module and a digital signal processor. The system can determine whether an electric special test vehicle is grounded effectively during the power-on test intelligently, and can carry out automatic protection if the electric special test vehicle is not grounded effectively, and thus the power-on closing test cannot be carried out. The detection system raises the test safety of an electric special test vehicle and protects safety of test personnel and test devices effectively.