Abstract: Based on the study of the Kalman filter blind adaptive multiuser detection and the linear conjugate multiuser detection，a linear conjugate semi-blind multiuser detection algorithm based on Kalman filter is proposed for MC-CDMA uplink.A linear conjugate semi-blind detector based on the MOE principle is designed by exploiting the spreading sequences of all known users and information contained in the pseudoautocorrelation of the observables.We combine the Kalman filter with the improved PASTd algorithm to obtain the weight vector adaptively.Compared with the Kalman filter blind algorithm，simulations demonstrate that the proposed method is not only effective，but also enjoys better SIR and BER performance，and has lower computational complexity.