The invention relates to a nuclear main pump thermal insulation device simplification equivalent analysis method. According to the method, a simplification equivalent model is established according toa general area equivalent method; the simplification equivalent model is divided according to the actual requirement to generate structured meshes, and wall meshes are encrypted to meet the requirement of flowing analysis of a turbulence model; and simulation analysis is performed on the simplification equivalent model. Through the method, in the simplification equivalent model, dispersed pipes,wedge-shaped slots and other complicated positions in a three-dimensional fine model are replaced through an equivalent through-flow area and circumferential speed constraint method, distribution of aflow field and a temperature field inside a nuclear main pump thermal insulation device can be well predicted, the difficulty of geometric modeling and meshing is effectively lowered, the calculationamount of numerical simulation operation is greatly reduced, the efficiency of the numerical simulation operation is improved, the performance of a preliminary design scheme can be quickly assessed,and the design cycle is shortened.