The assessment of aircraft damage is a key technology in modern flight missions. For a kind of ultra low altitude aircraft, simulation study of the damage caused by the prefabricated fragments is carried out, which is based on the functional systems contained in the different components of the aircraft. In addition, the corresponding aircraft damage assessment simulation system is developed, which can complete the real-time damage calculation and quantify and classify the damage degree of the functional system. A new modeling idea and important research platform is provided for vulnerability assessment and damage assessment of specific targets.