Abstract：In high-level radioactive waste deep geological disposal and deep mining，rock will exhibit rheological behavior under long-term thermo-mechanical coupling effects. In this paper，the rheological characteristics of three common components(elastic component，viscous component and plastic component) under thermo-mechanical coupling effects are discussed and the corresponding assumptions are made. Then，based on Nishihara model，the corresponding creep equation，unload equation and relaxation equation of Nishihara model under thermo- mechanical coupling effects are derived respectively. When the temperature factor is ignored，these equations will degrade to the original Nishihara model equations. These constitutive relations can broadly forecast the rock rheological failure time under specific temperature conditions，and the temperature change of the rock will reduce the rheological failure time. Normally，the greater the rate of temperature change is，the shorter the failure time of rock is. The approximate analysis indicates that the variable magnitude is comparative，namely，the change rate of temperature increase of one order of magnitude，the rock ultimate failure time will be shorted with one order of magnitude.
