For piston was easy to wear and return spring extension length was limited of the multi cylinder high pressure radial piston pump, a new pump combining spring external return mechanism with regular polygon driving mechanism was designed. The point contact of piston bottom surface was changed to surface contact, the abrasion speed was reduced, and the service life of the piston pump was increased. The modeling and simulation of the piston pump were carried out using SolidWorks for interference and collision analysis. Finally, a new type of radial piston pump was obtained.