For the problem of ground potential rise of DC cable sheath grounding network caused by AC cable inrush current fault when AC and DC cables are mixed in tunnels, this paper evaluates the risk of personnel electric shock and equipment insulation by studying the ground potential distribution. Firstly, based on the law of electromagnetic induction, the analytical expressions of DC cable sheath induced voltage and ground loop current under the fault condition of AC system are theoretically deduced, and the computational model of grounding network ground potential elevation is established accordingly. For the limited space constraints of the tunnel, four kinds of AC and DC cable laying methods are designed. Based on the electromagnetic transient software and grounding analysis software collaborative modeling, the transient potential distribution characteristics of the grounding network of the four laying methods in the AC system fault conditions were compared and analyzed, and the magnitude of grounding network ground potential rise was obtained, which was used as a basis for determining the optimal laying methods for AC and DC cables in the same tunnel, and the results also provided a basis for evaluating the possible risk of electric shocks and the risk of insulation of equipment.