The honeycomb sandwich panel (HSP) is constructed by two facing plates and honeycomb core. It has been said that the HSP has high specific modulus and strength because of the light core. Nowadays the HSP is applied to structural components in various industrial fields. HSP has lots of geometric parameters, facing thickness, core thickness, wall thickness and cell size and so on. For application of the HSP to structural components, the prediction of its mechanical properties would be very important procedure. In order to investigate influences of the parameters on the mechanical properties of the whole HSP, a simple numerical modeling method is proposed. A modeling method of honeycomb core will be an important key to the numerical modeling of the HSP. Considered the periodicity of honeycomb core, the core and adhesive layer are modeled by two kinds of beam elements. The facing plate is represented by shell elements. In this modeling, a use of the proposed model, eigenvibration analyzes are performed and compared with experimental results. After checking the validity of the proposed model, the influences of geometric parameters upon the eigenvibration properties are quantitatively discussed.