Abstract: High chromium white cast irons with different chemical compositions were heat treated by different ways. The relationship of friction coefficient and wear rate of high chromium white cast irons with friction power intensity, positive pressure stress, carbide phase and matrix structure were investigated by dry sliding friction and wear tests under low speed and heavy load. The mechanism of dry sliding friction and wear of high chromium white cast iron under low speed and heavy load was discussed. The results indicate that the friction coefficient of high chromium white cast iron was related to the type of carbide phase and positive pressure stress, but was not related to the matrix structure. The wear rate was concerned with the type of matrix structure, the type of carbide phase and friction power intensity. The microstructure of the cast iron was consisted of friction layer, rheological layer, strain band and stability region in sequence from friction surface to inside during dry sliding friction and wear test. The original matrix structure was severely damaged and fully mixed with broken carbide in the friction layer. The viscous resistance of solid phase plastic flow increased in the rheological layer resulted in the formation of crevices and caves, and fatigue flake occurred finally. The carbides in the strain band bent or was ruptured due to plastic deformation of matrix structure.