Abstract: In this papet, a simple optical synchronous CDMA multiple access interference surpress and cancellation scheme are proposed. The system uses modefied prime code(MPC). Each user is set a bank of correlator and the correlator's output power is queued in a network. Beacuse of the MPC's correlation characteristics, multiple user interference is surpressed. The algorithm can completely cancel multiple user interference when "0" signal is trasmitted. A part of multiple user interference cacelled as the remainder can enhance the user's signal power when "1" signal is trasmitted. The numerical results show that this method can decrease the BER greatly.