Abstract: The pitting damage of copper-based friction material by powder metallurgy was investigated in specific working conditions by the combination of clutch inertia test, the structure model of heterogeneous friction layer by powder metallurgy, and the temperature field of friction layer. The effect of temperature distribution on the pitting damage of friction materials was analyzed. The results show that, the pitting phenomenon occurs because of the temperature gradient and heat stress, resulting from the bonding areas of copper and graphite, when the wet copper-base friction material is overloaded or superheated. The pitting degree of the friction layer is gradually reduced from the lateral to the inside, and the most serious pitting phenomenon appears in the middle. In the same friction channel, the pitting phenomenon is more seriously far away from the radial oil groove.