Abstract: Nonlinear dynamics characteristics of symmetric rectangular honeycomb sandwich panels with completed clamped supported boundaries in primary resonance case were investigated using the homotopy analysis method(HAM). The honeycomb core of aluminum matrix was equivalent to a thick layer of orthotropic material whose equivalent elastic constants were calculated by the modified Gibson’s formula. Based on the classical laminated plate theory(CPT) and geometric large deformation theory, the forced vibration differential equations under transverse exciting force were derived. By means of vibration mode orthogonalization, the differential equations were simplified into dynamic control equations with dual-mode, and the average equations of primary resonance was obtained. Then the influences of different structural parameters on dynamic characteristics were studied. Numerical results show that the amplitude-frequency curves of honeycomb sandwich panels correspond to the response curves of Duffing equation with single degree. With the increase of the structural parameters, the obvious enhancement of the hard characteristic, and the remarkable decrease of the peak value of amplitude were observed. The conclusion can be applied to designing honeycomb sandwich panels and provide a theoretical basis for practical applications.