In order to detect potential fault hazards of grounding grid in time, a multi-dimensional fault risk assessment based on grounding safety detection is proposed. Based on the inference algorithm of fuzzy inference Petri net and fault tree, considering the influence factors and uncertainty of parameters in the space domain, time domain and frequency domain, a risk assessment model of substation grounding fault is proposed. Firstly, the relationship between multi-dimensional detection parameters of substation grounding network and grounding fault is analyzed. The basic event failure probability and its uncertain logic relationship are described by using graphical characteristics of a Petri net, and the failure risk probability is obtained. Then, the contribution degree of each influencing factor is calculated on the basis of Petri algorithm and fault tree to determine the contribution of the elementary event leading to the grounding device failure risk. Finally, grounding fault risk of the actual substation grounding grid is evaluated to verify the feasibility of the method. The research results can provide a basis for substation design and supply a reference for safety early warning of power equipment, which has engineering application value. This work is supported by Project of Xinjiang Uygur Autonomous Region Science and Technology Department (No. 2017D01C417) and Doctoral Initial Fund of Xi’an University of Science and Technology (No. 2017QDJ033).