[Objective] The early warning on the ecological security of watershed land in Fenhe River was studied to provide references for the scientific and rational utilization and sustainable development of watershed land resources.[Methods] The spatial and temporal pattern evolution characteristics and leading factors of land ecological security alertness in the basin from 2006 to 2018 were analyzed using a multiplier model, spatial autocorrelation, and a geographic detector.[Results] ① From 2006 to 2018, the evolution trend of the land ecological security alarm degree in the Fenhe River basin was a parabolic curve with upward opening, and it changed from the "less safe" to the "critically safe" state. ② Spatially, the ecological security alert degree of land was characterized by "large agglomeration and small dispersion" and underwent the process of "decline to increase." ③ The change in spatial autocorrelation of alertness experienced the process of "positive-correlation-negative-correlation-positive correlation," which was basically consistent with the spatial and temporal distribution of the ecological security alertness of the watershed land. ④ The leading factors affecting the land ecological security of the river basin for many years were the level of economic development, investment and governance of environmental protection, and land use efficiency.[Conclusion] In the future, the layout of production, living, and ecological space in the Fenhe River basin should be optimized. The ecological compensation mechanism of the basin should be established. Investment in environmental protection and scientific research should be increased to promote the ecological security level of the basin.