Design the pole-pitch variable long primary and short secondary linear induction motor, the permanent magnet secondary is located in the bilateral primary, and the object to be ejected is connected through the connecting device to complete the ejection acceleration task. The primary winding coil of the linear induction motor adopts the segmented power supply mode to improve the energy utilization rate of the electromagnetic ejection process. The influence of the extreme distance value on the self-inductance and mutual inductance parameters of the primary coil winding is simulated and analyzed. Establish a finite element simulation analysis model to analyze the magnetic field of the linear induction motor with variable pole pitch, and lay a theoretical foundation for the analysis of the variable pole pitch linear induction motor.