The invention discloses a space-time adaptive processing method based on a two-stage architecture, comprising steps of setting a quantity of array elements of a phased array radar as N, performing Doppler filtering process on time-space echo data xn received by the nth array element, obtaining output data yk, n of the nth array element in the kth Doppler channel so as to obtain the output vector of all Nth array elements in the kth Doppler channel, calculating the Q wave beams of the kth Doppler channel according to the output vector yk of all Nth array elements in the kth Doppler channel, and calculating the output data gk of the kth Doppler channel according to the Q space wave beams of the kth Doppler channel. The invention can obtain a better effect of inhibiting clutter in a side lobe clutter zone, can obtain a reasonable performance of ideally inhibiting clutter in the near-to-main-lobe clutter zone, can improve the signal-to-noise ratio of the target and improve the detection probability of the motion target.