Linear constrained constant modulus algorithm(LCCMA) and linear constrained differential constant modulus algorithm(LCDCMA) were studied in this paper.Using different signal amplitudes to simulate their convergence and stability,its results tally with the theory analysis.Simulation results show that the LCCMA can remove multiple-access interference completely if and only if the desired user’s amplitude is no less than the critical value 1/√3,however,the LCDCMA in all test situations can converge to desired user.It is superior to LCCMA in fast convergence and robustness.