Abstract: In order to study the creep characteristics of diorite porphyrite, triaxial creep tests of graded loading and cyclic loading-unloading were carried out to study the deformation and long-term strength characteristics of diorite porphyrite.Based on the test results, a damage creep model which can describe the viscoelastic plastic deformation of diorite porphyrite was established.The results show that with the increase of deviator stress, the axial deformation and lateral deformation increase gradually, and the volume deformation increases first and then decreases.The axial strain decreases first and then remains unchanged, and increases rapidly when the specimen is damaged.At the same deviator stress level, the instantaneous elastic strain is greater than the instantaneous plastic strain, while the viscoplastic strain is greater than the viscoelastic strain.More accurate and specific long-term rock strength can be obtained by the method of the relationship curve between steady state rate and stress ratio.Based on the characteristics of viscoelastic strain curve, a Kelvin model considering the attenuation of viscosity coefficient with time and stress is established.A viscoplastic damage model is established by paralleling Abel clay pot with plastic slider element and introducing damage variable, and a damage creep model of diorite porphyrite is obtained by connecting the two in series.The test curve is compared with the model curve and the fitting degree is high, which verifies the rationality of the model.