The invention provides a method and system for calculating a highway traffic blocking coefficient. According to the invention, coordinate points are marked at preset positions on an electronic map, real-time highway conditions of each coordinate point is acquired, a radar technology and a mode of reading Internet cloud data are adopted to respectively acquire a set of highway condition data in order to ensure the accuracy of the real-time highway condition data, final real-time highway condition data is acquired after performing fusion, study and judgment on the two sets of data, and the real-time highway condition data is classified according to dark red, red, yellow and green and marked on the electronic map. Whether the position where a certain serial number coordinate point is located is a congestion source or not can be accurately judged through judging highway conditions of the coordinate point and a downstream adjacent coordinate point thereof, and if the coordinate point is determined to be a congestion source, the blocking coefficient of the congestion source is acquired according to the difference between the highway condition data of the coordinate point and the highway condition data of the downstream adjacent coordinate point. Highway condition blocking coefficient data of all coordinate points on highways within the whole jurisdiction can be more accurately reflected by adopting the scheme provided by the invention.