The invention relates to an electric power steering device (EPS device) and a control method for the electric power steering device, comprising a torque sensor, a vehicle speed sensor, a current sensor, an electronic control unit (ECU), a power motor and a reducing mechanism; the electric power steering device also comprises a wheel static controller which consists of a transverse swing angular speed instruction generator, a state observer, a torque distribution controller and a tyre sliding controller. The EPS device and the control arithmetic of the EPS device compensate the problems of insufficient steering or over-steering due to the road surface or vehicle conditions, ensure the precise steering of the electric power system, ensure the normal steering of the automobile when the steering power system is failed and the steering power function can not be maintained by the EPS device, and have an guarantee failure safety control function. The control method of the invention adjusts the torque of all wheels under the situation of failure of the existing EPS system or insufficient steering and over-steering, forms the vehicle steering moment, ensures the completion of the steering action, completes the EPS failure safety control, and avoids the happening of the traffic accidents. The EPS device and the control method for the EPS device have the advantages of quick operation, reliable operation, low cost, etc.