The invention relates to an optimization method for off-road vehicle rear axle power distribution. A rear axle power distribution device is included and comprises an image collecting system and an ECU control system, the image collecting system is used for obtain pot hole image data information, and the ECU control system controls a differential mechanism to distribute the power to two wheels at a rear axle according to the obtained pot hole image data information. The image collecting system comprises a CCD camera, a line laser device and point laser devices. The point laser devices comprise the first point laser device and the second point laser device. The vertical position of the line laser device is located between the first point laser device and the second point laser device. The line laser device is parallel to the axis of the first point laser device and the axis of the second point laser device. The line laser device, the first point laser device and the second point laser device are inclined to a horizontal pavement. According to the optimization method for off-road vehicle rear axle power distribution, when an off-road vehicle passes through a pavement with pot holes, the rear axle power can be adjusted according to the pavement condition, and the passing ability of the off-road vehicle on the pavement with the pot holes is improved.