With the development of the wind power market, the power of the wind generator is gradually increased, and the volume is larger and larger, which brings difficulties to the direct drive generator transportation. When the outer diameter of the motor is greater than 5 m, the transportation cost will increase rapidly. In order to solve this problem, it is necessary to consider dividing the motor into several parts along the radial direction and transporting it to the project site for general assembly of the motor. After the motor is divided into segments, one coil cannot exist on two parts at the same time. The empty slot structure can effectively solve this problem. Firstly, the split technology of direct drive generator with the empty slot structure is presented. Secondly, the feasibility of the empty slot structure is analyzed by comparing the electromagnetic performance of the motor with and without the empty slot. Finally, the influence of the empty slot on the electromagnetic performance of the motor with different pole-slot combination is calculated. The feasibility of the empty slot scheme is proved.