Based on uniaxial unloading tests,stress-strain curves of rock specimens were acquired as well as their axial strain-lateral strain curves.Meanwhile,the rock specimens damaged in different degrees were obtained.By comparing with the complete curves before the strength peak,the segments of the stress-strain curves that correspond to unloading points of the rock specimens damaged in different degrees were determined.The damaged rock specimens and the broken rock were poured in concrete,and shear test on the concreted rock samples was made to acquire their shear strength.The results of test showed that if rock was unloaded in the stage of fracture stably propagating the shear strength of damaged rock slightly decreased,the change of strength might be concealed by individual difference of rock,but if rock was unloaded in the stage of fracture unstably propagating,especially was unloaded when the strength was close to the peak,the shear strength obviously decreased.The bocks formed in uniaxial compression failure still had considerable strength.