In view of the core requirements of lightweight permanent magnet linear synchronous motor (PMLSM) for catapult, this paper proposes a parametric modeling and optimization design method for unit motor based on finite element for the structure of long primary bilateral motor, and reveals the influence of mover length on the total electromagnetic weight of linear motor. Through finite element simulation analysis, the electromagnetic characteristics and mass relationship of the traditional PMLSM with toothed stator structure and toothless stator structure are compared. The manufacturability of two stator topologies of toothless distribution winding and cogged concentrated winding is compared and analyzed. The copper loss, iron loss, efficiency and power factor of the two structural forms under the same thrust output were quantitatively evaluated. The results show that the length of the end of the cogged concentrated winding can be shortened by 30 ~ 40%, and the copper can be saved by 15%, but at the same time, the total weight of iron increased threefold. Although the process of toothless distribution winding is complex, the total electromagnetic mass of the corresponding linear motor is reduced by 50%, the volume is reduced by 30%, the amount of permanent magnet is reduced by 25%, and the apparent power demand of the drive power supply is reduced by 20%, which is conducive to the lightweight of the system.