A new type of canned motor pump with extensive application value is designed, researched, and developed in this article. In order to grasp the characteristic of the internal flow field of the pump, the internal flow field is simulated numerically by using FLUENT software with the standard k– turbulence model, SIMPLEC algorithm, and multiple reference frame model. The distribution of the pressure and velocity of the flow in the canned motor pump is analyzed in different working conditions. Moreover, the head and efficiency of the pump is predicted based on the simulation results, which show that the head and efficiency of the canned motor pump in small flow rate will be better. The performance of the canned motor pump can be improved by appropriately increasing the outer diameter of the impeller and the base diameter of the volute. The results of the numerical simulation are in accord with theoretical analysis, which verifies the correctness of the numerical simulation. The investigations have important theoretical guiding significance for the design of the canned motor pump.