The invention relates to a preparation method of an epoxy corona-resistant nano material. The preparation method comprises the following steps: (1) mixing nano particles with epoxy resin, thus obtaining a first mixed solution, then performing magnetic stirring and ultrasonic treatment, and keeping a temperature range at 50 to 60 DEG C; (2) mixing a curing agent and the first mixed solution, and performing water bath stirring, thus obtaining a second mixed solution; (3) preheating a vacuum box, vacuumizing the second mixed solution, and pouring the solution into a mold; and (4) putting the mold into the vacuum box for vacuum treatment, and performing curing at normal temperature in vacuum. According to the preparation method, in the vacuum treatment and forming processes, under assistance of proper water bath temperature treatment, a relatively ideal bubble removal effect can be achieved under a laboratory condition. Under the laboratory condition, well preparation of a nano composite dielectric material is realized, and particularly the good bubble removal effect is achieved; and the preparation method has a good practical value for work of relevant scientific research and technical personnel.