Abstract The stochastic orthogonal polynomial expansion method is extended with the pseudo-excitation method in this paper. This extension enables the stochastic orthogonal polynomial method to be readily used in the analysis of stochastic parameter structures under non-stationary random excitation. The probabilistic information of structural response, such as the power spectral density, standard deviation function, etc. can be obtained directly with this method. A dynamic condensation algorithm for order-expanded equation resulting from the orthogonal polynomial expansion method is also presented in this paper. The applicability of the proposed methodology is demonstrated by numerical examples.