The scheme of 2-dimensions optical orthogonal square codes (2D - OOSC) in optical code-division multiple-access (OCDMA) networks is given in this paper. The influence of coding parameters to the performance of the system is mainly discussed. It is proved that the relativity of the codeword satisfies the system requirement, and the system BER based on multiple user interference is ascertained. The results indicate that the number of simultaneous users that can be contained in this system will be much larger than that in the system with ID-OOC under the same conditions, the total transmitting capacity of the system will reach the level of Tb/s, and the performance of 2D — OOSC system will be largely enhanced, especially under the heavy transmitting traffic.