The invention relates to an automatic positioning system for a railway unmanned inspection vehicle based on image recognition, and the system comprises an unmanned inspection vehicle and an industrial control computer. The unmanned inspection vehicle comprises a chassis system, a lifting mechanism and a mobile platform system. The chassis system comprises a chassis frame which is provided with a drive system and a first control cabinet. The lifting mechanism comprises an outer frame, a central frame, and an inner frame. The lower end of the lifting mechanism is installed on the chassis frame, and the upper end of the lifting mechanism is provided with the mobile platform system. The mobile platform system is provided with an industrial camera and a second control cabinet. The invention also discloses an automatic positioning method for the system. According to the invention, the industrial camera is used for collecting a picture of a vertical column of an overhead line system, and the features are stored completely and are very reliable. The image recognition technology has been very mature, and is wide in application range, so the image recognition can be used as a basis for the automatic positioning of the unmanned vehicle more reliably.