Abstract: Biaxially oriented polypropylene (BOPP) films are widely used as dielectric materials in film capacitors, and their electrical properties determine the energy storage characteristics of the capacitors. In industrial applications, modulation of the molecular structure of resin and optimization of the film stretching process are the key methods to enhance the energy storage density of BOPP. Therefore, six kinds of BOPP film samples were prepared by selecting two different polypropylene (PP) resins and changing the biaxially stretching temperature, and the molecular chain order and energy storage properties of BOPP films were tested and characterized. The results show that, on the one hand, the increase of stretching temperature is conducive to the orderly arrangement of molecular chains, and on the other hand, excessive temperature will exacerbate the disorientation of molecular chains. The ordered molecular chain arrangement can increase the activation energy of BOPP molecular chain segments, which can inhibit the carrier migration, enhance the breakdown field strength, and ultimately achieve the enhancement of energy storage density and the suppression of dielectric loss.