In order to restrain the multi-user interference that exists in optical code division multiple access(OCDMA) system,the on-off keying(OOK) is presently adopted as modulating method in most of OCDMA systems.Multi-user interference mainly has effect when bit 0 is transmitted;the reason is that there is no optical pulse at that case.Based on this idea,a novel method to suppress multi-user interference in OCDMA is presented,which is a new OCDMA system.It avoids no optical pulse existing while bit 0 is transmitted by adopting a spread spectrum code and its shift as the address codes of bit 0 and bit 1,respectively,and using the maximum value decision instead of the threshold decision.The fundamental of the system is stated,the optimal optical orthogonal codes is applied as address codes,the bit error probability of the novel system is derived and analyzed.Simulations based on the expression are done.The results show that the bit error performance of the novel system can be ten orders better than that of conventional system.