Abstract: Constant modulus algorithm (CMA)is a well-known blind adaptive beamforming method as it requires no pre-knowledge about the signal except that the transmitted signal waveform should have a constant envelope. The multistage constant modulus(CM) array is a cascaded adaptive beamforming system which can separate several narrowband co-channel signals without training. The main idea of the SMI-CMA is to use SMI to determine the initial weight for CMA operation. The method can output the desired signal in despite of the interfering signal is stronger than the desired signal. Computer simulations are presented to demonstrate the convergence properties and robustness of SMI-CMA .