1. A naked eye 3D video system for backing a vehicle, including: two cameras for being installed on a rear of the vehicle and configured to capture images of a scene behind the vehicle respectively; a processor configured to divide the images captured by the two cameras into image strips in equidistance respectively, and integrate alternatively the divided image strips together into integrated images by interleaving; a display device for being installed on an instrument panel of the vehicle and configured to display the integrated images in a form of three dimensions for a driver to watch with naked eyes; and a position detector configured to detect a distance between a nearest obstacle behind the vehicle and the vehicle on the basis of the captured images; wherein the position detector is configured to perform edge detection of the captured images based on a Sobel operator to determine a nearest edge in the captured images, identify a nearest obstacle that belongs to the nearest edge, and calculate a distance between the nearest obstacle and the vehicle based on installation positions and an angle between the cameras.