The reliability of monitoring and control directive communication is a crucial factor of GNSS control segment.As several high-speed communication links of CDMA system in a limited bandwidth of navigation satellite,the MAI (Multiple-Access Interference) would serious prejudice the stability and effectiveness of system.Traditional evaluation method simply based on C/N0 has a large error on BER for the particularity of MAI in limited bandwidth,which could hardly apply in control segment evaluation.To satisfied the need of the system stability and design of communication signal,put forward an accurate modeling and analysis which obtain a result of worst and best signal status of MAI,and put forward a analysis and evaluation method based on signal parameters included of PRN,code phase,polarization phase,cross-correlation distribution estimated parameter and so on.A test system of GNSS limited band communication was established,the test results prove the effectiveness of the method,and achieve the BER in the auxiliary of multi-user detection method of multi-channel high-speed communication system.The research achievements provide the basis for TT&C (telemetry tracking and command) of BeiDou control segment.