Abstract: For the purpose of exploring the influence of rheological characteristics on the system of surrounding rock mass-support structures for hydraulic tunnels, an analysis method to calculation time-varying reliability of tunnel support structure considering rheological characteristics of surrounding rock was introduced.Firstly, the analytical solution of viscoelastic-viscoplastic analytical solution for shotcrete supported circular tunnels was derived in hydrostatic stress field, by means of the Nishihara model based on the Mohr-Coulomb criterion.A bearing capacity reliability calculation function of anchor bolt was deduced according to the analytical solution of the displacement for inner and outer ends as well as the yield strength of the anchor bolt.Finally, the time-varying reliability calculation and analysis of shotcrete supported structures were proposed by an engineering example.The research results indicate that the rheological characteristics of surrounding rock had an essential effect on the displacement of surrounding rock and the deformation of anchor bolt, and the reliability index of the shotcrete support decreased as time flies and tended to stationary eventually.It was risky for the shotcrete support design if neglecting the rock rheological characteristics of the hydraulic tunnels with poor surrounding rock conditions.The research results can supply theoretical basis and method reference for the reliability evaluation of support structure stability of hydraulic tunnels.