Abstract: With the continuous development of components processing technology, the size of components unit is constantly reduced, and the working voltage is constantly reduced, so that the components' ability to resist single event effect is constantly reduced. This paper analyzes the fault propagation mechanism of the airborne data acquisition computer for an unmanned aerial vehicle (uav) under atmospheric neutron radiation. Combined with the improved FMECA method, based on the cause failure, the result failure and the contribution rate of the cause failure to the result failure, the fault propagation diagram of the computer is established, and the probability of occurrence of each underlying failure mode is obtained through layer-by-layer reasoning. A possible high-risk source location method is proposed. The possible high-risk fault source located at the system level is the core device FPGA of two single-boards on the computer.