A Burgers model with non-stationary parameters was presented in this paper based of the study on the shear creep experiments of the interlayer in Jinping Cascade 2 Hydroplane project. Because it takes into account the character of partial parameter that their value change with the passage of time

this model can not only describe the process of acceleration creep stage

but also is better than Burgers model with stationary parameters to describe the process of initial creep deformation and the process of steady creep deformation. Burgers model involve too many parameters

so particle Swarm Optimization (PSO) algorithm is adopted to identify the model parameters

and the results are satisfactory.