Abstract: Mechanical characteristics of granite under temperature (from normal to 1 200 ℃) have been researched with MTS 810 hydraulic servo system and MTS 652.02 high furnace.Theoretic expression of rock complementary energy discharge rate of visco-elastic damage by considering thermal-mechanical coupling has been derived based on irreversible thermodynamics theory.And the energy criterion of thermal-mechanical coupling damage fracture of granite has also been established.The result shows that peak strength and elastic modulus of granite decreases with rise of temperature and the complementary energy discharge rate of thermal-mechanical coupling damage increases with the rising of temperature and time.The time has great influence on rock failure process，so the time effect must be considered in theoretic analysis.The energy criterion established in this paper is more comprehensive and acceptable for dealing with rock thermal-mechanical coupling damage than the failure criterion established by traditionally single damage parameter.Research findings provide valuable basic references for solving problems of rock thermodynamics in reposition of nuclear waste，practical gasification of coal and oil shale，deep resources mining，exploitation of geothermal resources and safety withdrawal and comprehensive utilization of coal seam gas.

Key words: Granite, Thermal damage, Complementary energy, Visco-elastic, Energy dissipation