Abstract: The paper expatiates concisely the characteristics of coal mine industrial yard and the classification of grounding systems of low-voltage distributing system, and as well as the Applicable situations of each type of grounding system. Then the advantages and disadvantages of TN and TT grounding systems for road lighting are analyzed. Furthermore, the setting principle & method of the operating current of the RCD(Residual Current Operated Protective Device) in TT grounding system is expounded and the suggestion about how to select the reasonable grounding system for the road lighting is displayed.