Abstract: In order to measure aircraft fuel in any attitude, a real-time fuel measuring method based on CAD technique is presented. First, adopting 3D solid modeling technique, the model of fuel tank of some aircraft is established. The measurement principle with attitude error correction and the structure of the practical test system are then introduced clearly. Using the output data of fuel sensor and information of aircraft attitude, the real-time measurement and attitudeerror correction of aircraft fuel have been done. The experiment results illustrate that this method is very useful because of fast and accurate calculation.