The theory of natural frequencies were acquired from vibration experiment, meanwhile, the first order frequencies of honeycomb sandwich structure composites were obtained by using the sandwich laminboard theory and equivalent panel theory via the finite element software ANSYS. The simulation results were compared to the experiment results to get the error of calculation of the two different equivalent methods, thereby we can select more appropriate equivalent method to ensure the veracity of the result analysis and provide a reference for the optimization design of the fiber-paper honeycomb sandwich structure composites.