Abstract: A hierarchical adaptive fuzzy control system for an isolated urban traffic intersection is proposed, and an evolution strategy is used to modify the fuzzy membership functions of the system. This control system not only possesses the advantages of hierarchical fuzzy control, but also can change its membership functions adaptively to an optimal setting in different traffic situations, in this way the currency power of the urban intersection is improved. Simulation on an isolated four-approach intersection with through and left-turning movements shows that the presented controller can acquire lower average vehicle delay than the fixed-time controller and the hierarchical fuzzy controller with steady membership functions under various traffic conditions.