The electromagnetic balance head is used for balancing the electric spindle. This paper analyzes the internal structure of the electromagnetic balance head and introduces the structure of the counterweight plate and the range of the balance in the moving ring.The principle of how the electromagnetic field generated by the static coil acts on the moving ring is also investigated. The model is built in Ansoft Maxwell and the excitation parameters and boundary conditions are set up. Through the analysis of the magnetic field generated by the static coil in the position of the moving ring, it is verified that the static loop coil can drive the counterweight plate.