The pump is a coaxial series of two oil pumps, compact structure, installation is not limited by space, and low cost, motor and pump body is easy to decompose, easy maintenance. The double seal is used to minimize the oil leakage, and the pressure can be adjusted to minimize the motor load. When the sealing ring is made of fluorine-containing material, it can also be used at high temperature of 180 ° C, and the oil pump displacement can be combined according to the actual use requirements. It is suitable for the transportation of oil and fuel oil, the lubrication of machine tools and various industrial machinery, HV oil pump and ML motor.