Abstract: This paper focuses on the failure of automatic startup of fire smoke extraction fans, conducting an in-depth investigation using the fault tree analysis(FTA) method and the analytic hierarchy process(AHP). Initially, based on the current specifications for the startup linkage control of fire smoke extraction systems, the logical relationships and influencing factors leading to the failure of automatic fan startup are analyzed. A fault tree model is then developed and qualitatively analyzed using FTA software to solve for the minimal cut sets. Subsequently, the AHP is employed to allocate weights and conduct consistency tests for the model′s related factors, determining their importance. The research findings indicate that the primary causes of automatic startup failure in fire smoke extraction fans include faulty linkage control circuits, startup module failures, the controller being in a manual disable state, the control cabinet being in a manual mode, and mechanical failures of the fan. Based on these results, corresponding improvement measures and recommendations are proposed, providing theoretical guidance and practical references for the operation and maintenance of fire smoke extraction fans.