The invention relates to a method and a system for traffic light signal control based on wifi (Wireless Local Area Network) signal. The system comprises a monitoring center computer and a traffic light controller, wherein the monitoring center computer is used for installing traffic light operation scheme developing software and traffic light monitoring software on the computer; the traffic light operation scheme developing software is capable of deploying street lamps according to the site condition of a traffic crossing, developing a traffic light operation scheme in a graphic interface manner and carrying out simulated running, and is also capable of transforming the developed traffic light operation scheme into data files recognized by the traffic light controller; and the traffic light monitoring software is capable of displaying the information of each traffic crossing transmitted through the Internet in real time. In the system for traffic light signal control, the traffic light controller and a monitoring center carry out two-directional communication by means of a universal wireless network so that the monitoring center can remotely control and monitor the operation of the traffic light and simultaneously the purposes of remotely developing and amending the traffic light operation scheme can be reached.