This study utilized field monitoring data collected from sex pheromone-based intelligent traps for Spodoptera frugiperda in Nanping and Zhangzhou, Fujian Province, during 2019-2022. The HYSPLIT trajectory model was employed to reconstruct migration pathways, while upper-level wind field meteorological data during migration periods were analyzed using GrADS software to identify the source regions and migratory routes of fall armyworm populations invading Fujian in autumn. The results demonstrated that in the transitional migration zone (Nanping), the primary immigration period occurred from late September to mid-October, with moths mainly migrating from central-northern and eastern Zhejiang into northern Fujian via the southwestern route. In the year-round breeding zone (Zhangzhou), the primary immigration period was from early-October to November, with moths entering southern Fujian from southern Jiangsu and eastern Zhejiang through eastern Fujian. Overall, two migration routes (eastern and western pathways) were identified, collectively displaying a northeast-to-southwest directional pattern. The main source region is Zhejiang Province, with minor contributions from southern Jiangsu and western Shanghai.