A preparing method of a mebendazole intermediate (3,4-diaminophenyl)phenyl methanone is disclosed. The method includes adding 4-amino-3-nitro diphenylmethanone and a catalyst into an organic solvent, adding a hydrogen donor, and performing transfer hydrogenation reduction to obtain the (3,4-diaminophenyl)phenyl methanone, wherein the catalyst is a Pd-X / C catalyst, and the X is one of Ni, Ru, La, Ce, Co, Li, K, Mg, Ti, Cu or Mo. The method has advantages of mild conditions, simple operation, a high reduction rate, a low cost, high environment protection performance, easy industrial production, and the like.