Factor graph, so named because it graphically represents function factorization, with which and its sum-product algorithm the iterative algorithm can be deri ved clearly. An iterative multius-er receiver based on factor graph for asynchronous coded CDMA system is proposed. In this paper, the a posteriori probability of users information bits conditioned on the noise-whitening filters output is represented by factor graphs, after numbers of iterations with the sum-product algorithm the information bits are estimated. The authors also propose a reduced complexity algorithm. Simulation results show that with this proposed receiver, near-single-user performance can be achieved, and small performance degradation for the reduced complexity algorithm with signifi-cant complexity reduction. Factor graph, so named because it graphically represents function factorization, with which and its sum-product algorithm the same as iterative algorithm can be deri ved clearly. In this paper , the a posteriori probability of users information bits conditioned on the noise-whitening filters output is represented by factor graphs, after numbers of iterations with the sum-product algorithm the information bits are estimated. The authors also propose a reduced complexity algorithm. show that with this proposed receiver, near-single-user performance can be achieved, and small performance degradation for the reduced complexity algorithm with signifi-cant complexity reduction.