The invention relates to a method for applying oxidized PE wax to sealing protection of a circuit board. The method comprises the steps that the surface of the circuit board is coated with a layer ofcoupling agent, and air drying is conducted; the circuit board is dehumidified; a tackifier and a liquid toughening agent are added into the molten oxidized polyethylene wax to be uniformly mixed to prepare molten wax; the dehumidified circuit board is immersed in the molten wax for sealing, and after sealing is completed, the circuit board is placed on release paper and dried. By means of the sealing method, the defects that the oxidized PE wax easily cracks at the low temperature and has poor adhesion force are overcome; the tackifier and the toughening agent is added according to a ratio through repeated experiments, and finally, the oxidized PE wax can meet the requirement of the circuit board for effective waterproof and moisture-proof sealing in the working environment at minus 20-60DEG C. By means of the method, the good acid and alkali resistance, electrolytic-resistance chemical stability and hydrophobicity of the main ingredient PE wax are fully utilized, and a layer of waxfilm is formed on the surface of the circuit board and a component to protect the circuit board after melting.