The present disclosure provides a method and a device for detecting a height-limiting rod, and an automatic driving system, for use in a binocular stereo camera. The method includes: filtering out invalid points in a disparity map corresponding to a target image in accordance with a predetermined detection range, so as to acquire a valid point disparity map; projecting the valid point disparity map along an X-axis direction in a three-dimensional coordinate system onto a plane where a Y axis and a Z axis are located, and counting the quantity of valid points for each row of pixels with respect to each disparity value, so as to acquire a projection image; filtering out invalid projection points and invalid blobs in the projection image, so as to acquire a valid blob image; and back-projecting the valid blob image to the three-dimensional coordinate system, and determining a rectangular region where the height-limiting rod is located in accordance with X-axis, Y-axis and Z-axis coordinate values.