The invention provides a method and system for relieving the congestion degree of highways. According to the invention, coordinate points are marked on highways within the jurisdiction on an electronic map, wherein each coordinate point is provided with a unique serial number; a plan database is generated, wherein the plan database comprises video acquisition equipment IDs and congestion cause and countermeasure serial numbers; in allusion to each coordinate point on the highways within the jurisdiction, whether the coordinate point is a congestion source or not is judged according to highway condition data of the coordinate point and highway condition data of a downstream adjacent coordinate point; in allusion to each congestion source coordinate point, a corresponding video acquisition equipment ID and a corresponding congestion cause and countermeasure table are taken according to the serial number of the coordinate point, video images, which are acquired by the video acquisition equipment, of the congestion source are acquired, a congestion cause is determined, and a communication mode of the police on duty is determined according to the congestion cause; and the corresponding police is dispatched to the congestion site according to the communication mode of the police on duty so as to perform traffic dispersion, the congestion source is eliminated in the bud or the duration of the congestion source is shortened, and the traffic capacity of the highways is improved.