Hybrid excited synchronous machine (HESM) is a research hotspot, and its design method is worth to discuss. The motor stator is designed by ANSYS RMxprt software and the traditional magnetic circuit method, and ANSYS Maxwell software is used to design the mixed excitation motor rotor and the motor parametric modeling is conducted. Furthermore, the Maxwell & Workbench & OptiSLang co-simulation model of 8-pole 48-slot TMPS-HESM is established. Finally, the Pareto solution set is obtained by global multiobjective optimization of the motor using particle swarm optimization (PSO) algorithm. The technique for order preference by similarity to an ideal solution (TOPSIS) method is used to objectively select the optimal design scheme from the solution set. A co-simulation design method of tangential magnetizing parallel structure hybrid excitation synchronous motor (TMPS-HESM) based on PSO algorithm is systematically proposed, and the performance of the motor is verified to meet the design requirements by the relevant finite element simulation tests.