In order to analyze the anti-spoofing performance of the GNSS multi-beam anti-jamming receiver under spoofing interference scenario, a performance metric named deception suppression ratio was put forward. The theoretical formula for the power of the authentic and spoofed signal was deduced considering the anti-jamming receiver using the MVDR (minimum variance distortionless response) algorithm with limited number of snapshots. And the influence of the power of the spoofed signal arriving at the antenna array on the output power of the authentic and spoofed signal was analyzed in detail. The analysis shows that even if the power of the spoofed signal is below the noise level, the multi-beam anti-jamming receiver using the MVDR algorithm can still suppress the spoofing interference. And when the spoofed signal-to-noise ratio is high, the suppression is more effective. The conclusion was verified by simulation and hardware platform test.