Fabry-Perot cavities are used as frequency references for ultrastable optical oscillators. The deformation of cavity induced by the vibration degrades the length stability of the cavity and laser produce frequency noise. Finite element analysis (FEA) is often used to examine the deformation of the cavity at arbitrary acceleration. A general expression of the change of the cavity length induced by the displacements and tilting angles of the cavity mirrors is deduced. This expression provides the definite connection between the cavity deformation and the vibration sensitivity. Based on this method, it is analyzed that the vibration sensitivity of a horizontal optical cavity, and its sensitivity to vibration can be reduced by optimizing the mounting configurations. In addition, a compact vibration platform that is able to shake the optical cavity in three orthogonal directions is designed.