Considering the time effect of surrounding rock and the long time stability of the underground caverns after being excavated, a method on the finite element viscoelastic displacement based on Kelvin model. The recursion formula is obtained by the displacement analytic solution of Kelvin model. It can be used to predict the viscoelastic displacement development fast and accurately. Finally this method is employed into a project, and the calculated values by this method agree well with the measured values. Prove that the method is effective.