Abstract: Based on a particle flow discrete element model and PFC^2D code, a numerical rock sample with block mass of 1 cm in radius located at the middle was built. Three sample types (A、B and C) were constructed by changing block mass micro-mechanical parameters with 0.1, 1 and 10 times, respectively, and all samples were conducted a triaxial compression test and a triaxial fatigue test. Their mechanical properties were studied through investigating rock fracture as well as measuring stress and strain ratio. The results show that:stress concentration is triggered above and below the block in the A-type sample under triaxial compression test and triaxial fatigue test loadings, while the low stress regions are located at the left and right side of the block mass. No stress difference is observed in the B-type sample. The amplitudes of strain ratio in block mass of the A-type sample is larger than that of the around, while the C-type sample is contrary. No strain ratio difference is observed in the B-type sample. The study reveals that 1) block mass with no matter high or low strength reduces to rock compression strength; 2) rock with block mass presents both non-uniform stress and deformation fields under static or cyclic loading.