A method and device for judging intercity transportation modes based on mobile phone data solves the problems of difficult data acquisition and low data processing efficiency in the existing solutions. The method includes: obtaining the trajectory of each user from the mobile phone data; extracting an intercity traffic sub-trajectory in the trajectory of each user; and judging the transportation mode of the intercity traffic sub-trajectory. The solution has the advantages of easy data acquisition, high data processing efficiency and capability of achieving long-term monitoring.