[Objective] The ecological security status of cultivated land was evaluated and its obstacle factors were diagnosed in Dongting Lake plain, in order to provide reference for rational utilization and pollution control of cultivated land.[Methods] The ecological security evaluation index system of cultivated land in Dongting Lake plain was established based on DPSIR model. From the county scale, the improved TOPSIS method based on entropy weight was used to calculate the cultivated land ecological security status in Dongting Lake plain from 2007 to 2017. And the obstacle degree model was employed to diagnose the main obstacle factors of cultivated land ecological security status.[Results] The ecological security degree of cultivated land in Dongting Lake plain was in a critical state from 2007 to 2017. The comprehensive index of cultivated land ecological security fluctuated and increased slowly during the study period. The change characteristics of cultivated land ecosystem security in different counties were different. The main obstacle factors restricting the ecological security of the cultivated land system included the improved proportion of medium and low yield field, the proportion of straw returning, the proportion of soil testing and formulated fertilization, the intensity of pesticide use, the intensity of plastic film use, the intensity of fertilizer use, and the proportion of agricultural natural disasters.[Conclusion] To improve current ecological security status of cultivated land in Dongting Lake plain, comprehensive land consolidation should be implemented and agricultural non-point source pollution control should be strengthened.