Abstract: The study on three sets of rock samples has shown that granite rock sample has greater cohesion duo to higher content of quartz, fractures located at grain boundary will remarkably decrease tensile strength of rock sample, feldspar is the main source of brittle rock sample, cohesion of rock is significantly influenced by grain size and foliation structure, aplite granite has lower compressive strength and Young's modulus due to its higher content in calcite; Chemical sedimentary rock samples have the characteristics of dilation or creep for dense packing of halite crystals. Organic materials in salt rock decreased mechanical properties; The weak zones located in the boundaries of grains or between matrix would deteriorate the mechanical behavior of rock samples, quartz cement in dark gray mudstone has the feature of secondary growth,which can raise the mechanical properties of dark gray mudstone.