With the continuous improvement of avionics system, the traditional method of safety analysis is difficult to guarantee the completeness of failure mode as it is too dependent on engineering experience. And in the process of system iterative design, due to the complexity of the system, the workload of safety analysis is too large, which increases the time and cost. Aiming at the above problems, an automated safety analysis tool was designed, the safety data model was established based on SysML, automatic fault tree was built by using route tracing method, and the common mode analysis and zone safety analysis were carried out on the generated fault tree. The experimental results of a system show that the tool can realize the automatic modeling and analysis of the fault tree and improve the efficiency and competeness of the safety analysis.