Aiming at the problem that the soft insulator of pulse motor can not accurately describe its state and regular in the actual working process, a soft insulator opening test system was designed, which approximately simulated the working process of the soft insulator in the pulse motor. The opening characteristics of the ablative and non ablative soft insulator were compared, and the deformation law of the ablative and non ablative interlayer from the mechanism was explained by the means of scanning electron microscope. The test results show that the ablation rate calculated by the ablation simulation test is approximately equivalent to the insulator of a test pulse motor, and the relative error can be controlled within 5%; the deformation of the non ablated insulator is “valley pile” and the deformation of the ablated insulator is “bulb”. The established soft insulator layer opening test system can provide a feasible technical approach and means for the design and test verification of the soft insulator of pulse motor.