In order to improve traffic management and reduce energy consumption in urban road traffic,the relationship between the traffic flow status and the fuel economy of road traffic is investigated by introducing the concept of economical fuel-consumption saturation and presenting the evaluation parameter of fuel economy. Then,based on a large number of field-measured data of fuel consumption,the evaluation models of fuel economy are established respectively for expressway,trunk road,secondary trunk road and branch,and the economical fuel-consumption saturation for the above four types of roads in Harbin is figured out. The results of model validation show that the proposed models can accurately describe the relationship between the traffic flow status and fuel economy,thus providing the theoretical basis for the improvement of traffic management from the viewpoint of energy saving.