Cross-linked polyethylene (XLPE) cables are the first choice for urban grid line construction. Insulation defects can lead to partial discharge, which affects the insulation performance of the cables and even leads to insulation breakdown and line tripping. At the same time, the cables undergo constant hot and cold cycles during operation, and the insulation layer temperature affects the partial discharge characteristics of XLPE. In order to study this effect, a pin-to-plane electrode experimental platform is set up to measure partial discharge data of XLPE at different temperatures, and the results show that partial discharge mainly occurs at ?10°~100° and 150°~265° of the frequency cycle, and its distribution looks like “rabbit ears”; an increase in the insulation layer temperature will lead to an increase in the number of partial discharges and a decrease in the initial voltage of partial discharges. The above experimental findings are verified by simulating the partial discharge phenomena under the influence of insulation layer temperature by using a joint COMSOL-MATLAB analysis to model the pin-to-plate structure with an air gap. The results show that the introduction of an air gap can explain the variation of partial discharge of XLPE with insulation layer temperature in the pin-to-plate electrode, and the variation of XLPE dielectric constant with temperature is the key reason for the decrease in the initial voltage of partial discharge. The results help to explore the mechanism of partial discharge of XLPE affected by insulation layer temperature, which is important for the analysis of the partial discharge signal of cables and cable condition assessment.