ABSTRACT: As a good material in engineering, diamond can be used in many fields. However, natural diamond is scale and expensive, so people make synthetic one using chemical vapor deposition (CVD). But polycrystalline CVD diamond films have rough and non-uniform thickness which can adversely affect their application. Furthermore, it is difficulty to machining the CVD diamond thick-film.In this paper, the studies on the machining of CVD diamond thick-film were carried out. Laser processing and mechanical polishing are used to machining the CVD diamond thick-film. The major research work is included as follows:1. Studies on mechanism of the laser processing the diamond were carried out. The laser heats up the diamond and causes the temperature rises on the surface of diamond film. At the different temperature, the different physical and chemic change will happen. The rules of the laser ablating diamond were researched by experiment.2. On the basic of theory, experimental studies on laser cutting and polishing diamond film were carried out. In this paper, Q switch Nd:YAG laser was used to polishing the diamond films. The incidence angle of laser beam and other factors have been found to result in more effective polishing, with optimal best smoothing observed at incident angles of 75 ? . The electron microscope and Raman spectra were used to analyze the diamond films after laser processing.3. Experimental studies on mechanical polishing diamond film were carried out. The primary investigation was carried out using mechanical polishing equipment. The diamond films after polishing were observed by means of scanning electron microscope. The machining process and the factors which influence the polishing efficiency and quality were preliminary discussed.