Abstract: Analyzing the mineral composition of 8 kinds of rock types by XRD, and characterizing surface morphology of polished rocks by 3-D white light interferometer, frictional coefficients of 8 kinds of rock types in natural, saturated and dry conditions are investigated by means of the self-designed test apparatus. The experimental results indicate that the frictional coefficients relate to the mineral composition. The increment amplitude of frictional coefficients under saturated and natural conditions is greater than that under dry and natural conditions for silicates composed by multiple-stripe minerals. The increment amplitude of frictional coefficients under saturated and natural conditions is much smaller than that under dry and natural conditions for carbonates composed by multiple-stripe minerals. The variation of frictional coefficients of rocks composed by homogeneous mineral is larger than that of rocks composed by multiple-stripe minerals.