The invention provides a method and a device for positioning a lane where a vehicle is. The method applied to a base station comprises the steps of obtaining road condition information of a road where the vehicle is; obtaining an average vertical distance value between the vehicle and the base station within a preset time period; determining a distance between the base station and each lane of the road based on the road condition information of the road and the position information of the base station; and determining the lane where the vehicle is based on the average vertical distance value and the distance between the base station and each lane of the road. According to the embodiment, the lane position where the vehicle is can be calculated by obtaining the distance between the vehicle and the base station within the preset time period, the distance between the base station and each lane and the road condition information of the road where the vehicle is; the purpose of positioning the vehicle position based on the single base station is realized, the construction cost of a base station positioning network is reduced, and base station resources are saved; and the method and the device for positioning the lane where the vehicle is are suitable for and applicable for an application form of the current intelligent traffic in which a single roadside node is set according to a road section, and can be put into use rapidly.