Abstract：By making use of the 20 MN servo-controlled triaxial rock testing machine with high temperature and high pressure of China University of Mining and Technology，the experimental studies of creep properties of large-size granite specimens of f 200 mm×400 mm with temperature up to 600 ℃ and axial stress up to 175 MPa are carried out. This research reveals：(1) Under three-dimensional stress，the axial creep deformation at 300 ℃ and 500 ℃ and volumetric creep deformation at 300 ℃，500 ℃ and 600 ℃ of Lu Gray granite show three stages：primary creep stage，stable-state creep stage and accelerating creep stage. (2) Under high temperature and 3D stress，the volume，length and radius of Lu Gray granite increase with time because of fissure caused by thermal cracking in rock. The lateral deformation was more rapid than axial deformation at the same time. (3) It¢s the basic hypothesis of visco-elastoplastic problem under three-dimensional stress that differential stress causes axial creep；hydrostatic stress causes volumetric creep deformation based on experimental data；and the volumetric creep constitutive equation of Burgers model under three-dimensional stress is also proposed. (4) Through the analysis of creep curve，it¢s proper to simulate axial creep at 300 ℃ and 500 ℃ and volumetric creep at 300 ℃，500 ℃ and 600 ℃ with Burgers model and to calculate model parameters.
