Diamond film was synthesized on Co-deficient (Co content is about 0.5%) WC-Co substrate using microwave plasma chemical vapor deposition (MPCVD) equipment without special pretreatment. SEM, XRD, Rockwell-indentation test and scratch test were used to analyze the structure and morphology of the diamond film and its adhesion to the substrate. Co content was also measured by EDAX. The results show that the film synthesized is of ideal diamond structure with perfect and uniform grains, dense and continuous surface and strong adhesion. Co content on the surface of the substrate is about 0.8% after 20h deposition, which is considered as one of the main causes to get good adhesion.