Recently, wireless sensor networks are used in an expanded bulk of utilizations. In this research, a lighting control system is proposed on basis of wireless sensor networks named LACS (Lighting Automatic Control System). This system with the ability of explaining the users' activities, in addition to providing the needed lighting which provides the satisfaction of users, will provide energy saving and management. In this paper the particles of LACS, their way of relationship, and decision making algorithm are discussed. Meanwhile algorithm prevents waste of energy by reduction of relation with sensors at the time of decision making. The possibility of collecting information for offering various reports, and the possibility of regulating the accuracy level of the system are other facilities of the proposed system. Finally there is a real scenario offered on the proposed system and system assessment according to the production level of lighting intensity and the level of system accuracy is done.