Satellite navigation receivers are highly susceptible to electromagnetic interference, and array-based space-time or space-frequency adaptive processing has been proved to be the most effective anti-jamming method. In actual engineering implementation, the channel mismatch is inevitable. Thus in this paper, the impact of channel mismatch on the performance of GNSS antenna array was evaluated according to the statistical evaluation method. The results show that, group delay bias and amplitude mismatch between channels are the two main factors leading to the deterioration of anti-jamming performance. The influence of the former can be eliminated by increasing the number of taps of space-time filter, while the latter is not sensitive to the number of taps and the necessary calibration is required.