Abstract: The technology of OCDMA has many advantages in access network. The design of great capability address codes is the precondition to practicability of this technique. In this paper, on the basis of constructing the 2D prime code, we put forward a kind of space/frequency/time 3D code for OCDMA system. It's based on prime sequence arithmetic. The results of the theory analysis and methematic computation show that, comparing with the 2D code, this 3D code has larger capacity, lower BER, higher bandwidth efficiency and better performance.