At present, HVDC capacitors widely use polymer film as the solid dielectric material, and the cost of polymer film accounts for about 70% of the production cost of capacitors. The quality of the polymer film directly affects the capacitor's capacity stability, voltage resistance, safety and its life cycle and other performance indicators. The history of the development of power capacitors is essentially the history of the development of power capacitors with dielectric materials. It can be said that the development of dielectric materials is the basis for technological progress of power capacitors. With the development of capacitors to the direction of low loss, miniaturization, capacitor solid dielectric materials experienced cable paper, capacitor paper, polymer film and capacitor paper composite, and finally to all the polymer film development process. 1920s, to kraft paper as a solid dielectric foil capacitors in the United States was born. In the 1970s, polypropylene (PP) film capacitor dielectric changes, followed by the emergence of paper-film composite dielectric, to the 1980s, the use of polypropylene film is much more than the use of paper media, in the 1990s, polypropylene film has become a power capacitor's main dielectric material.