The good interface insulation performance at the interface of the electrical connector is one of the key factors to ensure the safe and stable operation of the cable system. In this paper, the breakdown voltage and leakage current of different insertion structures are tested experimentally. It is found that the single cone structure of soft and hard insulation coordination can ensure the close contact of the insertion interface and has good insulation performance. Based on this structure, this paper takes single cone structure of SIR/PTFE soft and hard insulation coordination as the research object. Through simulation and experiment, it is concluded that SIR can tolerate the high temperature caused by contact resistance at the insertion position, and when the interface pressure is 0.2 MPa, the insulation performance of SIR/PTFE insertion interface is the best.