Preparation method of insulating layer of power transformer

The invention discloses a preparation method of an insulating layer of a power transformer. The preparation method comprises the steps of adding methyl vinyl silicone rubber, ethene-octylene copolymer and butadiene rubber, and stirring the mixture for 5-10 minutes at the temperate of 80-100 DEG C; adding linear low-density polyethylene, flame retardant and antioxidant, and stirring the mixture for 2-5 minutes at the temperature of 80-100 DEG C; adding a vulcanizing agent, a cross-linking agent, an antistatic agent, nano-silica and tetrahydrofuran, and stirring the mixture for 15-25 minutes at the temperature of 40-50 DEG C; subsequently, raising the temperature to 60 DEG C, conducting fast stirring for 2.5-3.5 hours, and obtaining a mixture; applying the mixture uniformly to the surface to be coated of the power transformer, drying the surface at the temperature of 120-130 DEG C, and obtaining the insulating layer of the power transformer. According to the preparation method of the insulating layer of the power transformer, the elastic ethene-octylene copolymer and the thermoplastic linear low-density polyethylene are mixed with the silicone rubber, so that electricity leakage caused by expansion of the insulating layer due to high voltage heating can be effectively prevented.