Network Coding - We propose and investigate a novel scheme of delay attack-resistant network based on optical code division multiple access (OCDMA). The bit error rate (BER) is analyzed theoretically, and the closed expression of BER is obtained. The system has a corresponding optimal threshold to minimize the BER in different cases. At the same transmission power, the BER will decrease when the code weight increases. Furthermore, the maximum number of users is different with different code weight and transmission power. Optisystem simulation results show that OCDMA system has delay attack-resistant performance, which can effectively improve the physical layer security of optical network.