The invention discloses an electric desalting method and belongs to the technical fields of petrochemical engineering and resource utilization. The electric desalting method is used for solving the problems that the existing electric desalting equipment is large in size and low in desalting and dewatering efficiency. An electric desalting tank is radially separated into a plurality of layers; a water interception and guide device is arranged at the bottom of each layer; water settled on each layer is intercepted and guided to a water bag, and the settled water drops on the upper layer are prevented from entering the lower layer. The invention also provides a water interception and guide plate, a water collection tank and drainage pipe equipment for realizing the method disclosed by the invention. According to the method and equipment, the desalting and dewatering efficiency is greatly improved. The method and equipment are used for crude oil desalting and dewatering, particularly applied to desalting and dewatering heavy crude oil.