A method and system for adjusting traffic lights. The method and system can dynamically divide a region according to the road congestion situation and adjust traffic lights in a resulting control region according to the control region, so as to solve the traffic congestion problem. The system for adjusting traffic lights includes: a congestion determining module, a control region determining module and a adjusting module, wherein the control region determining module is configured to determine a control region according to a dispersion demand of a first phase and a dispersal capability of a corresponding phase of an adjacent intersection, and the adjusting module is configured to adjust traffic lights of at least one corresponding phase of an adjacent intersection in the control region so as to relieve the traffic congestion situation at the first phase of the first intersection. Also described is a corresponding method for adjusting traffic lights.