The invention discloses a Ti/TiN/MaN composite coating on the surface of a cutter. The Ti/TiN/MaN composite coating is divided into three layers, namely a Ti transition layer, a TiN layer and an (Al, Ti, Cr) N layer in sequence outwards from the surface of the cutter, wherein the thicknesses of the Ti transition layer, the TiN layer and the (Al, Ti, Cr) N layer are respectively 50-200nm, or 100-500nm or 2-5Mu m; the tissue structure of the Ti/TiN/MaN composite coating is a nanocrystalline structure; the (111) surface diffraction intensity I of the Ti/TiN/MaN composite coating in X-ray diffraction is lower than 400 and the surface of the Ti/TiN/MaN composite coating is 22-33GPa in hardness and 1-2-level in indentation grade. The invention also discloses a preparation method of the Ti/TiN/MaN composite coating. According to the invention, because a plasma reinforced intermediate-frequency reactive magnetron sputtering technology is used as the preparation method of the composite coating, not only is sputtering evaporation of various reactants facilitated, but also the obtained Ti/TiN/MaN composite coating is dense in tissue, high in purity, flat in surface, high in binding force with a cutter and good in wear resistance, the segregation of film components can be furthest restricted, the ionization rate and the deflection property are greatly improved, and therefore the life of the Ti/TiN/MaN composite coating in cutting machining of stainless steel is prolonged by 50-100 percent; and in addition, the Ti/TiN/MaN composite coating is simple in process, easy to master and control and is convenient for industrial production of a cutter coating.