Abstract: Honeycomb sandwiches used as hulls and floor panels of high-speed train and other transportation vehicles require not only excellent mechanical stiffness/strength but also good sound insulation performance. The vibroacoustic performance of a finite rectangular honeycomb sandwich panel with simply supported boundary conditions is investigated analytically. The vibration governing equation of the structure is established by applying an equivalent method for the honeycomb core and Reissner's theory for sandwich panels. With sound pressure introduced into the vibroacoustic governing equation in the form of double Fourier series, the resultant equations are solved numerically in conjunction with fluid-structure coupling condition. Numerical simulation results with the method of finite elements are employed to validate the analytical model, with excellent good agreement achieved. The developed model is used to investigate the influence of several key system parameters on sound transmission of the structure, including the core thickness, honeycomb wall thickness, in-plane panel dimensions and sound incidence angles. The model presented here holds great practical potential for the optimization design of honeycomb sandwich structures.