In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experiment of isolation performance evaluation based on LMS Test. Lab Signature software. The comparison results of four different vibration isolating systems show that the peak values of vibration velocity response in each system mainly appear at 25Hz, 50Hz, 75Hz and 100Hz, and the maximum velocity does not exceed 22mm/s which is less than the maximum allowed by the national standard. And the Vibration Level Difference (VLD) is taken as evaluation criteria for isolating vibration, that of single-layer vibration isolating system is within 10-20dB, and that of double-layer vibration isolating system is within 20-35dB. Furthermore with the increase of middle-mass, the VLD has a clear upward trend.