A visible light access control system based on mobile phone flash is designed. The popular rear camera flash of mobile phone controlled by a written is used as a light source,then optical signal is modulated,and ID information and sy stem password are sent to the access control system.The access control system eq uipped with optical signal receiving circuit can receive the optical signals,and demodulate the ID information and password are demodulated.If the password is the same as the initial setting ,access control is unlocked. At the same time,the system has attendance function by identifying the owner′s ID information.The system is sensitive and reliable,low cost and easy to use.