Currently, aircraft registration number recognition is still done by human beings in most airports. This recognition method is not only time-consuming but also energy-wasting and cannot meet the demand of busy airport. To solve this problem, a method of aircraft registration number recognition automatically is proposed in this paper. This method, based on image processing, mainly discusses how to identify registration number and confirm the identity of the aircraft automatically after registration number positioning, segmentation and identification. The experiment results show that this method has a high rate of accuracy in the aircraft registration number recognition, thus automation level and staff working efficiency of the airport can be improved by using this method.