Abstract: The intrinsic characteristics of all-composite honeycomb core sandwich panels （ACHCSP） were investigated using a combined approach of theory and experimentation. A theoretical model of the ACHCSP structure was established based on the high-order shear deformation theory and Gibson equivalent theory. The dynamic characteristics of this structure were determined using the Rayleigh-Ritz method and orthogonal polynomial approach. A relevant experimental platform was constructed to conduct tests on ACHCSP as the research subject， thereby confirming the accuracy of the theoretical model. The results indicate that this theoretical model can accurately predict the natural frequencies of ACHCSP plates. Based on the established model， the influence of fiber layer thickness， honeycomb cell wall thickness， and wall length on the natural frequencies of ACHCSP structures is discussed.