The invention provides a machine vision technology-based intelligent light bar acquisition system and a method for obtaining outer contours of railway tracks. The intelligent light bar acquisition system comprises a detection trolley, a UPS power module, an image acquisition module, a control system and a software system. The intelligent light bar acquisition system and the method can be used fordetecting conventional detection parameters of tracks; automatic acquisition and automatic control are imported, so that the working intensity can be greatly reduced; through a sliding block, a laseradjustment bracket is adjusted to slide leftwards and rightwards, so that two sides of the tracks can be directly detected; an encoder is capable of correctly detecting a movement distance of the trolley, recording a detection distance and a detection position, and controlling the movement and stop of the trolley according to the detection distance, so as to realize automatic control of the trolley; when the trolley stops, the image acquisition module acquires a target image and a background image; an image processing method adopts a difference method, so that the adaptation, to complicated environment, of the detection trolley is improved; and by adoption of ARDUINO UNO, the control system has the characteristics of being correct in control, high in speed and low in cost.