Frequency response analysis is performed out under the application of the self-weight of the rotary compressor as the force on the model with in the Frequency range of 0-100 Hz. This particular range is selected since the working range of frequency of the compressor is from 50-60 Hz. In Harmonic analysis, displacement is measured in the frequency range of 0Hz to 100Hz dividing the frequency range into 10 sub steps. The response of the system to this excitation frequency is measured at the three locations that are at each Leg. A node near to each leg is selected and at that node, its displacements are measured along all the directions. Analyzing all the three mounting plates using Harmonic Analysis, the displacement response in the plates with the range of excitation frequency is determined. Considering them sequentially 211mm plate, 176mm plate and 176mm flat plate responses are determined and compared their stability.