The invention discloses an intelligent transportation system for relieving congestion, and an operation method thereof. The intelligent transportation system for relieving congestion comprises a datamanagement module, a vehicle monitoring module, a weather monitoring module, a variable lane management module, an electronic speed limit display screen and a power supply module, wherein the vehiclemonitoring module is laid on a photovoltaic road surface to monitor the vehicle driving speed and the road traffic flow information, thus being able to effectively monitor whether a vehicle is speeding and identify the information of an illegal vehicle through a radio frequency identification technology so as to effectively supervise the traffic order; the variable lane management module is used to adaptively change left turn, right turn or going straight of the vehicle according to the congestion condition of an intersection; the weather monitoring module is used to monitor the weather condition in real time; and when bad weather appears, such as rain, snow, fog and haze, the data management module correspondingly adjusts the speed limit indicator and displays through the electronic speedlimit display screen to prevent the situation that a driver drives the vehicle overspeed when he or she cannot see a speed limit board because of poor visibility caused by bad weather, thus reducingoccurrence of traffic accidents.