The invention belongs to the technical field of machining of the pressure-bearing pump bodies of slurry pumps and particularly relates to a surface machining method for the pressure-bearing pump bodyof a slurry pump. The surface machining method includes: preparing coating powder, and spraying wear-resistant coating to the surface of a pump body. Compared with the prior art, the surface machiningmethod has the advantages that a certain quantity of quaternary phosphonium salt modified montmorillonite is added into conventional metal ceramic powder, and the quaternary phosphonium salt modifiedmontmorillonite which is compact in structure and small in inter-particle gap can effectively enhance the adhesive force of the coating on the surface of the pump body; the pump body is treated undera low-temperature condition and then preheated in a short time, part of pores can be formed in the surface of the pump body in a short time, the adhesive force between the coating and a shell can befurther enhanced, bonding strength reaches 140MPa or above, the surface of the coating is smooth, the operation process is simple and controllable, good wear resistance is achieved, and the service life of mixed media of water and solid particles conveyed by the centrifugal slurry pump can be effectively prolonged.