The work aims to improve the interface bonding capacity between diamond and the substrate. First, the diamond powder was treated within the sequence of “removing organic matter-degreasing-roughening-drying”. By using homemade CVD device, the process of plating tungsten on diamond surface by CVD with H2 and WF6 as reactive gases was studied. Micro morphology, composition and microstructure of the diamond powder coating tungsten were analyzed by means of scanning electron microscopy (SEM), electron spectroscopy, X ray diffraction (XRD) and transmission electron microscope (SEM). Preliminary testing was performed in respect of diamond powder covered with coating. The best technological parameters for obtaining uniform and dense coating on diamond surface with particle size of 223.6 ?m were: deposition temperature of 670 ℃, deposition time of 2 min, H2 introduction quantity of 1 L/min and WF6 consumption of 2 g/min. When the deposition temperature was 580 ℃, thickness of the uniform and compact coating was 150 nm, and less impurities were present in the coating. Bending strength test was performed after hot pressed sintering between tungsten-coated diamond and copper power, common diamond and copper powder. Test results showed that, bending strength of tungsten-plated diamond sample increased by 38.6%, the coefficient of thermal expansion coefficient of the sample containing tungsten-plated diamond lock block was lower than that of ordinary diamond. The more power was added, the coefficient of thermal expansion was lower. Surface properties of the tungsten-plated diamond particles are improved, and the binding capacity of the substrate is improved.