Diamond membrane which was synthesized on the cemented carbide tool surfaces by Chemical Vaporate Deposition (CVD) with tungsten filament heating was investigated. Abrading tests of these coated tools were performed on a lever experiment apparatus. The experiment results showed that the wear width of uncoated tools 1.6 times as large as the one of diamond coated tools. The peeling of diamond membrane restrains the coated tools from decreasing tool wear with high extent.