The invention relates to a device and method for preparing an electrically assisted gradient coating on a fuel cell plate base material, comprising a conveyor belt, a current controller, and a plurality of rolling assemblies, and the current controller is respectively connected to the conveyor belt and each rolling assembly, The rolling assembly includes a base roller, a roller cover and an adjustment device. The roller cover is set on the base roller, and the composition of the roller cover is the material to be coated; The Joule heat generated in the suite melts the material to be coated, and the material is coated on the surface of the metal substrate through the movement of the conveyor belt. By setting up multiple coating coating stations, the effective preparation of the gradient coating is obtained. Compared with the prior art, the invention has the advantages of smooth coating surface, good mechanical properties, one-time molding, convenient processing and high efficiency.