To explore the impact of source coding on light fidelity（Li-Fi） technology, this paper studies four different source codes methods: non return zero（NRZ） code, return-to-zero（RZ） code, carrier suppressed return-to-zero（CSRZ） code and double binary code, and builds the Li-Fi system based on wave division multiplexing（WDM） by using OptiSystem software to discuss the performance influence of the four codes on the Li-Fi system based on WDM. The simulation results show that the NRZ code type performs well in transmission distance at 10 Gb/s transmission rate and CSRZ code type shows strong anti nonlinear performance and advantages in transmission distance at 40 Gb/s transmission rate.