Array processing is widely used to achieve anti-jamming and multipath mitigation in GNSS(Global Navigation Satillite System) receivers for its ability to provide spatial resolution. According to different influences of interference and multipath signals to the signal processing in GNSS receivers, a two-stage anti-jamming and multipath mitigation structure divided by the correlation integrator was proposed. In the first stage, before despreading the space-time covariance matrix was estimated and anti-jamming was realized by using the subspace projection technique with the assumption that the interference power was bigger than the sum of GNSS signal and noise. In the second stage, spatial smoothing was used for multipath decoherence, and then a beamformer based on GSC (Generalized Sidelobe Cancellation) method with householder transform was implemented for multipath mitigation. Theoretical analysis and simulation results show that the proposed method can effectively suppress the strong interference and can significantly reduce the multipath signal effects on code measurement of GNSS receiver.