Abstract: This paper studies the time-frequency vibration characteristics of grid-stiffened plates under stationary/nonstationary random excitations. With the help of the smeared stiffener method and Hamilton’s principle, the stiffener with different grid sizes is equivalent to a laminated composite plate with a base layer and a stiffened layer, and the governing equations under general boundary conditions are derived. By combining the method of Reverberation-ray matrix (MRRM) and the pseudo-excitation method (PEM) organically, a new global-domain stochastic dynamic analytical analysis method- RRM-PEM is proposed, which unifies the matrix formulas under the base acceleration in the frequency domain and the moving random excitation in the time domain, making it suitable for fast evaluation of the time-frequency characteristics of the structure in the transform domain. Meanwhile, the derivation of the separation of the non-homogeneous dynamic equations from the generalized state vectors reduces the dimensionality of the scattering matrix, thereby effectively decreases the numerical instability in the inverse Laplace transform process. By comparing with the results from the finite element simulation, it is proved that the analytical model of the grid-stiffened plate established in this paper is reliable and efficient in solving various stochastic excitations. Meanwhile, a series of engineering cases for the power spectrum density (PSD) and time-varying root mean square (RMS) further reveal the effects of stiffened parameters, load velocity and frequency band on the random vibration of the grid-stiffened plate.