Abstract: In order to analysis the stabilized and isolated ability of control system, the model of two-level stabilization system was established and the controller was designed.The result of simulation showed that the bandwidth of rate stabilized loop was improved to 200 Hz, the isolation at 1 Hz reached -90.1 dB. The error of line of sight(LOS) was measured by position-sensitive detector (PSD),the result of isolation testing experiment showed that the position isolation at 1 Hz reached -73.1 dB,increased by 20 dB approximately,which implied that the stabilized precision could be improved significantly by two-level stabilization system.