Suppression of multiple access interference （MAI） is one of the key technologies in wireless optical CDMA systems. The cause of generation of MAI is analyzed and the suppression methods of MAI are given: optical hard limiter （illustrated in an OCDMA system with prime code） and multiple user detection （MUD

illustrated in an OCDMA system with 2-dimensions code）. Results show that optical hard limiter technology can only suppress MAI partly while MUD can eliminate MAI effectively. MUD technology is proposed as a good scheme to eliminate MAI in wireless OCDMA systems.