Abstract: An accurate formulation to predict the thermal post-buckling load carrying capacity of orthotropic circular plates based on von Kàrmàn nonlinearities is reported in this paper. The governing differential equations of circular plates with orthotropic material properties are converted into linear differential equations employing the nondimensional parameters. The radial edge load is evaluated by assuming suitable admissible functions for the lateral displacement. Simply supported and clamped boundary conditions are considered in this study. The Rayleigh - Ritz method of total potential energy gives the values of linear buckling load. The thermal postbuckling load of orthotropic circular plates is evaluated using the radial edge load and linear buckling load. The influences of suitable admissible functions on the lateral displacement are also discussed. The numerical results obtained from the present investigation are compared with the known results reported in the literature and are in good agreement within the engineering accuracy. The error percentage of the results has been predicted and a maximum error is found out to be 4.02 % for simply supported and 3.67 % for clamped boundary conditions respectively.