A direct sequence spread spectrum scheme for visible light communication system is proposed. The spread spectrum scheme is based on the Shannon theorem in information theory. Theoretical analysis result demonstrates that spread spectrum technology can mitigate the effect of multipath and improve the security in visible light communication system. The simulation results show that the performance of direct sequence spread spectrum based system is improved comparing with the directly detecting system without spread spectrum. Spread spectrum is a practical approach to improve the reliability of the visible light communication system.