In view of the fact that the current full duplex systems cannot effectively deal with external interference, a joint algorithm based on self-interference suppression technology and adaptive beamforming technology, is proposed for eliminating self-interference and external interference simultaneously. Firstly, the system model of the full duplex arrays under this scenario is established. Then, according to time-domain cancellation method and Minimum Variance Distortionless Response(MVDR) method, the mathematical model as well as the performance analysis of the algorithm is derived. At last, the numerical simulation results indicate that the proposed algorithm can restrain both self-interference and external interference to the noise level.