For　the　two　kinds　of　rock　materials,　grey　mediun-grained　clay　feldspathic　sandstone　and　microlite　dolomitic　marble,　by　means　of　Schmidt　hammer　test,　X-ray　diffraction,　scanning　electron　microscope,　the　formation　mechanism　of　exfoliation　and　its　effect　on　the　mechanical　properties　of　rock　surface　are　analyzed.　The　results　show　that　the　exfoliation　has　an　important　effect　on　the　mechanical　properties　of　rock　surface.　It　has　an　obvious　difference　of　mechanical　properties　variations　between　different　kinds　of　rocks　with　different　exfoliation　shapes.　The　flaking　and　scale　exfoliations　of　the　two　kinds　of　rock　materials　have　more　effects　than　granular　exfoliation　of　microlite　dolomitic　marble　on　the　mechanical　properties　of　rock　surface.　This　difference　is　caused　by　the　different　mineral　components　and　textures　of　the　two　kinds　of　rock　materials.