Abstract: In view of the unsafe and inefficient problem of judging the distance between locomotive and carriage from the manual operation, an image ranging system was designed. Through the installation of the camera at the rear of the locomotive, it collected real-time video between the locomotive and the car information, and solved the unsafe and inefficient problems caused by manual look-up during the dispatching operation and implemented the effect of intelligent distance measurement and warning. Using improved SIFT(Scale-invariant feature transform) feature image matching algorithm and fixed-focus translation series of image ranging technology, under the OpenCV2.4.9 and Visual Studio 2012 configuration environment, the real-time distance measurement results were got and displayed on the upper computer interface of the driver's cab, which provided real-time monitoring. Besides, the distance alarm loop could also be set up on the upper computer interface, which implemented the purpose of intelligent ranging and reduced the work intensity and accident rate of the workers.