The invention discloses a diamond coating layer drilling/milling cutter grinding pretreatment method. The method comprises the following steps: firstly, the surface cobalt removal pretreatment is performed for a hard alloy drilling/milling cutter; then, resin particles and diamond micropowder are mixed to prepare sand blasting and grinding powder; a resin-diamond mixing sand blasting and grinding device is used for performing the sand blasting and grinding treatment on the surface of the cutter to uniformly remove a matrix material on the surface of the cutter; and a hot wire chemical vapor deposition method is used for performing the diamond film deposition on the pretreated drilling/milling cutter. The method is high in grinding efficiency, simple and convenient in operation, uniform in material removal, incapable of damaging the cutter edge and more prominent in grinding of the cutter with complicated shape; and on this basis, the hot wire chemical vapor deposition method is used for performing the diamond film deposition on the pretreated drilling/milling cutter, so that the coating layer flatness can be improved, the coating layer surface activity is improved, and the effect of improving the interlayer adhesive strength is achieved.