Abstract: In the global navigation satellite system(GNSS),space-time adaptive processor(STAP) technology has been the chief method for interference suppression.However,the processor can induce different cross-correlation peak biases to different satellite signals,which could degrade the positioning performance.In order to evaluate the bias induced by STAP algorithm and thus provide theoretic guidance for selecting satellites subsequently,the space-time adaptive processor is modeled to a FIR filter structure,whose response depends on the signal's frequency and arrival direct.The bias can be estimated by the cross-correlation peak of the reference signal and the FIR filter output.Finally,simulations with this method are presented to analyze the C/A code cross-correlation peak biases induced by STAP with minimum variance(MV) and minimum variance distortion response(MVDR) criterion.Results show that the impacted scope is larger when interferences are illuminating from the low elevation angle,and STAP with MV criterion induces more bias than MVDR.