Automatic identification system （AIS） satellite receive r can receive signals from different cells with the same frequency band， and thes e signals form co channel interference (CCI). Suppressing CCI is one of t h e most challenging issues of the AIS system. A simple serial receiver structure consisting of a direction of arrival(DOA) estimator, a beamformer and a demodulat or is proposed. In this structure, incident angles of all desired and int erference signals estimated by multiple signal classification (MUSIC) and Capon are given. Then minimum variance distortionless response (MVDR), minimum mean square error (MMSE) and matched filter (M F) beamforming algorithms are employed to make the steering vector align with the incident direction of the desired signal to suppress the undesired interference signals. Finally, a two bit differential demodulation algorithm is applied to d etect the useful signal. The simulation results show that the proposed structure, co mpared with the single receiving antenna, significantly suppresses C CI and notably improves the bit error rate (BER) performance of Gaussian filtered minimum shift keying (GMSK) by using mu ltiple antenna beamforming.