Aiming at the problems of large deformation and early damage of surrounding rock in deep buried tunnel under high temperature, high pressure and high humidity environment, based on the classical Cvisc constitutive model, the constitutive model of surrounding rock considering creep damage and weakening coefficient of surrounding rock material is deduced theoretically. The rationality of the constitutive model is verified by comprehensive methods such as numerical simulation and field monitoring. On this basis, the creep range and section deformation of deep tunnel surrounding rock under dry and damp softening states are compared and analyzed. The results show that the Cvisc constitutive model considering damage and weakening coefficient of surrounding rock material can better describe the relationship between surrounding rock deformation and time in deep environment. The surrounding rock of tunnel is mainly viscoelastic deformation in creep stage. The softening state has obvious time effect on the damage of surrounding rock, which makes the creep range of damp softening state expand after 18 days compared with dry state. The change of tunnel section under dry and damp softening states is asymmetric. The change shape under dry condition is approximate deflection diamond, and the change shape under damp softening state is approximate deflection trapezoid, and the change of tunnel section under damp softening state is greater than that under dry condition.