In order to make up the deficiency of the present numerical and analytical models of porous material, a new semi-analytical model is established for the vibroacoustic analysis on a thin rectangular porous plate. In this model, by applying the elastic theory of thin plate, and introducing the membrane resultant force and moment which are relative with the acoustic pressure of the fluid media in the porous plate, according to Biot theory in the 3 dimension case, the constitutive equations and the corresponding relationship between the internal force and displacement of the porous material in 2 dimension case is obtained. Then, combining the equilibrium equations for the frame with the motion governing equation for the fluid media, through Fourier expression expansion and dimensionless manipulation on every variable in these equations, and eliminating the intermediate variables, a vibroacoustic governing matrix equation for the porous plate in frequency domain is acquired. It is expressed in the form of a first order ordinary differential matrix equation, and can be solved in precise by the extended homogeneous capacity high precision integration method. Coupling motion effect between the in-plane direction with the transverse direction is considered in the present model, which is more close to the actual case for the porous plate. Moreover, employing the extended homogeneous capacity high precision integration method, the computational accuracy for the vibroacoustic problem of a porous plate in the medium-high frequency range can be ensured. Taking a thin rectangular porous plate with the two boundaries simply-supported as an example, the coupling effect on the vibroacoustic performance is demonstrated.