The invention discloses a preparation method of an abrasion-resistant coating of the sealing surface of a high-temperature and high-pressure oxygen valve. The preparation method comprises the following steps that S100, a ball base body is pretreated; S200, a bottom layer of the coating is prepared through a hypersonic flame spraying technique; S300, a ball is milled and ground; S400, ultrasonic cleaning is conducted on the ball; S500, ion cleaning is conducted on the ball; and S600, a surface layer of the coating is prepared on the surface of the ball through a magnetron sputtering technique. The preparation method of the abrasion-resistant coating of the sealing surface of the high-temperature and high-pressure oxygen valve has the advantages that the abrasion-resistant coating prepared on the surface of the ball of the high-temperature and high-pressure oxygen valve through the method is high in hardness, good in abrasion resistance, low in friction coefficient, compact and free of pores, and leakage of the valve is completely avoided when pressure testing is conducted in a high-pressure state.