The invention discloses an application of a porous ceramic membrane catalyst with a waste rare earth-based denitration catalyst as a raw material. In the invention, with a porous ceramic membrane prepared from the waste rare earth-based denitration catalyst, silicon source powder, activated carbon powder and a forming agent solution as a carrier, and metal nickel or silver as a catalytic active component, the porous ceramic membrane catalyst prepared by the invention not only can realize high-added-value resource utilization of the waste rare earth-based denitration catalyst, but also can efficiently catalyze and reduce water pollutants such as p-nitrophenol, methyl orange, methylene blue and the like, and is environment-friendly and low in cost.