This paper introduces a new method to construct zero cross correlation (ZCC) code for spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems. Its construction is based on an identity matrix which characterized by: flexibility in code weight and simple construction steps. According to numerical results, SAC- OCDMA system has better performance using our proposed ZCC code comparing with dynamic cyclic shift (DCS) and random diagonal (RD) codes in term of BER thanks to zero cross correlation property. Where, it can enhance the system capacity up to 3.26 and 1.76 times, and data rate is also enhanced about 5.75 and 3.02 times comparing with DCS and RD codes respectively.