The invention discloses a 
capacitor film with biaxially oriented 
polypropylene as a base body and a preparation method thereof. The 
capacitor film comprises the raw materials in parts by weight: 68-72 parts of biaxially oriented 
polypropylene, 23-28 parts of LDPE (low-density 
polyethylene), 10-15 parts of homo-
polypropylene, 3-5 parts of 
epoxy linseed oil, 2-3 parts of polyving akohol, 1-2 parts of 
aluminium hydroxide, 1-2 parts of polyisobutene, 8-12 parts of diatomite, 1-2 parts of 
ferrocene, 0.7-0.9 part of poly-4-methyl-1-amylene, 10-12 parts of K-
feldspar powder, 1-3 parts of nanosilicon dioxide, 0.9-1.1 parts of 2,6-di 
tert butyl phenol-alpha-dimethylamino 
phenol, 1-3 parts of 
calcium stearate, 1.4-1.6 parts of phenyltriethoxysilane, and 1.7-2.3 parts of modified tree ash. The biaxially oriented polypropylene serving as a primary material, low-density 
polyethylene serving as an auxiliary material and a plurality of auxiliary materials are mixed, extruded and subjected to film blowing, shaping and 
cutting to prepare the 
capacitor film. The capacitor film is simple in preparation method; and the diatomite, the K-
feldspar powder, the nanosilicon dioxide and the modified tree ash are added to the materials at the same time. Therefore, the barrier property and the gas tightness of the film are increased; and the capacitor film has good resistance to pressure and 
shock resistance, and has the characteristics of 
high heat sealing strength and good heat sealing property at the same time.