This paper proposes a method of interference suppression for a random planar array.Orthogonal transform are performed certain times on the signals.Then an average covariance matrix can result from all the covariance matrix of the transformed signals and from which a weight can be determined by a rule of Max SNR.The validity of the method is illuminated by computer simulation.And the method can constrain the interference efficiently and has no limits about the correlations among the interference signals.