Abstract: The roof of coal mine roadway has a special layered structure of coal-rock,so it is of great significance to study the strength and deformation characteristics of coal-rock single body for the control of roadway stability.In this paper,taking Hanzui Coal Mine in Shanxi Province as the engineering background,the true triaxial tests of coal samples and rock-like material were carried out respectively by the self-developed true three-axis electro-hydraulic servo control system of China University of Minging and Technology.The influence of intermediate principal stress on their strength and deformation under true triaxial condition was analyzed.The study resluts show that their peak strength and peak strain first increases and then decreases with the increase of intermediate principal stress,which is affected by the minimum principal stress.In the process of increasing intermediate principal stress,the failure of coal samples experienced from shear failure to splitting combined shear failure.In addition,when the intermediate principal stress is too large,they will experience the transformation process from ductility to brittleness.The above phenomenon shows that the intermediate principal stress plays a role of first restraining and then promoting the failure of coal and rock.