Compared with natural diamond(ND) and Polycrystalline diamond(PCD) tools, chemical vapor deposition(CVD) diamond tools have not only excellent physical and mechanical properties such as great hardness, low coefficient of friction, highest thermal conductivity, chemical stability, but also have the excellence of low cost、flexible size and shape. So they have been used successfully in machining various materials, such as Al alloys, Cu alloys, Fiber-reinforced plastics, graphite, wood, and so on. Unfortunately, the weak film-substrate adhesion and the high price of equipment used for depositing diamond films are significant drawbacks for the wildly commercial applications of diamond film tools. In the present work, diamond films were deposited on Co-deficient Cemented Tungsten Carbide by microwave plasma chemical vapor deposition (MPCVD). By means of scanning electronic microscope, effect of pre- treatment、deposition time and methane concentration on mophology of the diamond films were investigated. Results show that diamond on WC-Co substrate without any pretreatment has low nucleation density and poor crystal. With the increase of methane concentration, grains of diamond grow denser and smaller which results in lower surface roughness.