Abstract: In order to alleviate the heat damage caused by high temperature in deep wells and explore the thermal insulation performance of the polyvinyl chloride (PVC) backfill, thermogravimetry, thermal conductivity, specific heat capacity and micro−morphology of the backfill with 0%~20% PVC powder were measured. The results showed that adding PVC powder can improve the thermal insulation performance of the backfill; PVC particles were combined with the backfill to form a dense and uniform structure. However, due to the weak adhesion of PVC, excessive PVC powder could lead to a loss of adhesion between the components of the backfill, an increase in internal pores and cracks, and a decrease in the compressive strength of the backfill. The compressive strength showed a trend of first increasing and then decreasing with the content of PVC powder. Under the conditions of a slurry mass concentration of 78%, a cement to sand ratio of 1∶4, and a PVC powder replacement cement content of 10%, the backfill had the best performance. At that time, the compressive strength was the highest, at 10.782 MPa, the thermal conductivity was 0.921 W/(m·K), and the decrease was the largest. The specific heat capacity was 1.391 kJ/(kg·K).This article analyzed the thermal properties of PVC powder backfill, providing new ideas for alleviating thermal hazards in deep well mining.