In order to meet the requirements of honeycomb sandwich plate of an optical small satellite on the weight and stiffness, and to reduce the dynamic response of components on honeycomb sandwich plate, the equivalent theory and dynamic analysis of honeycomb sandwich plate were studied. First of all, the equivalent theory of the hexagon honeycomb core and the face sheet with adhesive layer were introduced. Then, the finite element model of -Y honeycomb sandwich plate of an optical small satellite were established, and the optimization analysis of the honeycomb core parameter with the weight and dynamic stiffness as the goal was performed. Analyzing and comparing the weight and stiffness of different core, finally, the honeycomb core of 0.03 mm in thickness and 5 mm in length was chosen. And then, on the basis of modal analysis, sine vibration and random vibration analysis are performed on the honeycomb sandwich plate. Finally, the sine and random vibration test are carried out. The experimental results and analytic solution showed that the first natural frequency error is 1.9%; the sine acceleration response error is 4.5% and the random acceleration response RMS error is 3.7%. These indicated that the analysis model is established accurately, the equivalence of parameters is reasonable and the dynamic analysis is accurate, and thus could meet the dynamic response requirements of satellite integration and each single component on the honeycomb sandwich plate.