In order to know more accurately the rock mechanical properties of hot-dry rock reservoir under high temperature， and further guide the drilling work of hot-dry rock， the real-time Brazilian splitting test， shear test and uniaxial compression test under high temperature were carried out in laboratory. In a single test， rock samples taken from the same borehole and the same depth were loaded at a rate of 0.1mm/min by setting the temperature and holding temperature time using a high-low temperature chamber， to reduce the adverse influence of the discretization of rock macro-mechanical properties and the deviation of test process on the test results. The samples are monzonitic granite taken from the Well LGZK1 in the Wendeng-Rongcheng-Weihai area of Shandong province. Through obtaining the maximum load and deformation data of the samples at failure， the mechanical properties such as tensile strength， shear strength， compressive strength and elastic modulus are calculated， and the failure mechanism and strength difference of the rock under real-time high temperature are analyzed. As a result， the shearing strength and uniaxial compressive strength of granite increased and the tensile strength decreased below 200 °C. While the shear strength and uniaxial compressive strength of the granite decreased and the tensile strength continuously decreased with the increase of temperature. The increase of temperature and stress will increase the hardness and plasticity of the rock. It provides basic parameters for the study of rock mechanical properties of the high heat flow granite， and also provides a reference for the selection of rock-crushing tools， drilling technology and wellbore stability in the exploration and development of high heat flow granite type hot-dry rock resources.