Abstract: Multiuser detection in Code-Division Multiple Acess(CDMA) system is an effective method. The Partial Parallel Interference Cancellation(PPIC) detector is considered as an effective yet simple receiver. However, the optimal cancellation level which is controlled by Partial Cancellation Factor(PCF) is usually determined by trial and error, since no theoretical values were reported. A multiuser receiver employing two-stage PPIC based on MMSE criteria is introduced in this paper. Computer simulation shows that the derived PCF is insensitive u the estimation bias of the noise level and the interfering signal power.