Abstract: The problem of the free vibration of simply supported circular plate when temperature field and strain field are coupled is studied in this paper.A system of nonlinear differential equation is obtained by Galerkin's method.The numerical results of coupled fields are compared with those of the uncoupled fields. It is found that if the given initial displacement is smaller, the fundamental frequency of circular plate in coupled case will be larger than that of the uncoupled case. If the given initial displacement is larger, the fundamental frequency of circular plate in coupled case will be smaller than that of the uncoupled case. Some effects of coupling coefficient on vibration are also discussed.