[Objective] In view of the operational requirements of the shielded motor for aviation pumps under special working conditions, as well as the issues of high loss, low efficiency, and complex structure in traditional shielded motors, this paper proposes a shielded motor for aviation pumps based on internal and external dual water circulation. [Methods] Through in-depth analysis of the structural characteristics and design index requirements of the shielded motor for aviation pumps, the water friction loss and shielded sleeve losses that affected the motor performance were analyzed and calculated in detail, and the performance differences of different shielded sleeve materials were compared. Starting from the key parameters such as air gap length and shielded sleeve thickness, a parametric scanning was performed to comprehensively analyze the effect mechanisms of these parameters on motor performance, which provided the basis for the selection of main electromagnetic parameters of the motor. In addition, regarding the variable load starting characteristics of the motor, the actual load carried by the motor was used as a reference to fit the starting characteristic curve for variable load starting analysis. Considering the fluid dynamics factors, the finite volume method and finite element method were applied to analyze the stress distribution characteristics of the motor and shielded sleeve under different temperatures through the fluid-solid coupling. [Results] The multi-physical field coupling simulation and experimental results showed that the reasonable selection of the length-to-diameter ratio and air gap length of the motor could effectively reduce water friction losses. The poly-ether-ether-ketone was selected as the shielded sleeve material, and its internal stress could fully meet the strength requirements. Meanwhile, under the load condition, the error between the output torque of the prototype and the simulation results was 1.7%, and the maximum error in no-load rotational speed was 0.66%, proving that the motor could effectively meet the requirements of special operating conditions. [Conclusion] The experiment verifies the rationality and feasibility of the design, providing theoretical basis and practical reference for the optimization and design of shielded motors for aviation pumps.