A method is proposed for calculating the vulnerability of aircraft to spray fragments of a missile. The input data of aircraft or components for vulnerability assessment is organized by the finite element models. First, the 'shot line scanning method' is used to calculate the single-hit vulnerability of aircraft by a fragment of missile. Utilizing Markov-Chain method, the vulnerability of aircraft is obtained at the threat of multiple hits by spray fragments. An example that shows the distributions of probability of kill at the typical missile detonation locations around the aircraft has been provided. In this example, the interaction regions of aircraft with fragments of missile are analyzed and the correctness and feasibility of the proposed method are demonstrated. Application shows that (1) the proposed method is generic and easy to be programmed; (2) to provide a realistic and effective aircraft vulnerability assessment, the method has taken into consideration the factors such as missile velocity, missile detonation location, missile charge ratio, fragment shape, air drag, aircraft altitude, and aircraft velocity; (3) the vulnerability assessment of aircraft to fragments of missile is useful for aircraft survivability enhancement design, missile effectiveness assessment, and optimizing missile fuse design.