An efficiency explicit iteration algorithm for nonlinear systems subject to nonstationary stochastic seismic excitation is proposed based on the equivalent linearization. Firstly, the nonlinear systems are transformed into the discrete linear systems using equivalent linearization method. And the explicit timedomain iteration algorithm is then deduced based on the Newmarkβintegration method. The proposed algorithm is finally applied to a MDOF VanderPol system and a MDOF Duffing system under random nonstationary process. The results verify the high accuracy and efficiency of the proposed explicit iteration procedure.