The invention discloses a plasma spray gradient wear-resistant plate and a preparation method and an application thereof. A layer of Fe50 Fe-base self-fluxing alloy is applied to the pretreated surface of a carbon steel substrate as a transition layer in a plasma spray mode, and the hardness of the transition layer is 48 to 52 HRC; then a two-channel powder feeder is adopted to synchronously feed powder on the surface of the transition layer, one channel is used for feeding plasma spray reaction powder, the other channel is used for feeding Fe50 Fe-base self-fluxing alloy powder, and the powder feeding speed of the two-channel powder feeder is adjusted, so that the hardness and toughness of the wear-resistant layer on the surface are further adjusted, and the wear-resistant layer of which the hardness is 58 to 65 HRC is obtained; and the plasma spray reaction powder is composed of Fe, Ti, Cr, Ni, W, Al, B4C, TiC and SiC. According to the preparation method, the density and binding force of a coating can be increased, and gradient distribution of the ceramic phase content from the surface layer to the transition layer and even the substrate can be realized, so that the binding force of the coating is further increased.