Polypropylene metallized film capacitors are the core devices of HVDC converter valves, electric vehicle DC/DC converters, pulse power supplies and other devices. In recent years, electrical equipment has been developing towards large capacity, high power and miniaturization, and the operating temperature of capacitors has been rising. At high temperature, the conductivity loss of polypropylene film increases sharply and the breakdown strength decreases significantly, which has become the bottleneck problem restricting the high temperature application of metallized film capacitor.