Ansoft Maxwell software is used to simulate and calculate the electromagnetic part of the shiftsolenoid valve. The effect of with or without magnetic isolation tank on electromagnetic force was analyzed and compared. Besides the effect on electromagnetic force and air gap was analyzed mainly from three aspects: the angle, length and position of the diaphragm of magnetic isolation tank, and the variation law of the electromagnetic force was analyzed. The design of the shift solenoid valve provides a theoretical basis for magnetic isolation tank. The results show that the length and position of the magnetic isolation tank have a great effect on the electromagnetic force, and the angle of which has little effect on the electromagnetic force within a certain range.