Toroidal motor is a new-style electric machine. In this paper, the basic principle of the motor is introduced. The forming and controlling of the rotational magnetic field are explained. The worm coil distributions for the motor are investigated. Based on the coordinate transforming principle, equations of the stator and the center curve for the worm groove are deduced and the 3D worm and stator models are constructed. The principle experiment was done and equation of the speed ratio for the motor was proved. The results are useful for the analysis of the toroidal motor.