Clarifying the driving mechanism of cultivated land use eco-efficiency is a key basis for deepening the frontier exploration of land science and optimizing the development pattern of food security. This paper constructed a triple-security framework of "border-food-ecology" and applied the super-efficiency SBM model of undesired output to measure the eco-efficiency of cultivated land use in China-Vietnam border area from 2000 to 2020. We also studied its evolution characteristics and regional differences through the Theil index and used the dynamic panel system GMM model to reveal the driving mechanism. The results showed that: (1) The cultivated land use eco-efficiency index in China-Vietnam border area generally showed a trend of "first rise, then drop, final rise", and the overall efficiency was at a medium level. The overall spatial distribution exhibited a pattern of "north high and south low", and inter-provincial differences were the main reasons for regional differences. (2) Excessive use of chemical fertilizers, labor surplus and increased carbon emissions were important factors for the slack input and output of the cultivated land and the loss of eco-efficiency. (3) The change of the cultivated land use eco-efficiency in China-Vietnam border area was driven by multi-factor interaction. Terrain slope, urbanization, border trade level and financial support for agriculture were positive factors to improve the eco-efficiency. The rate of water-soil loss, industrialization and the scale of cultivated land per labor had inhibitory effect on the eco-efficiency. China-Vietnam border area urgently needs to optimize the input structure of cultivated land management, transform to the direction of "excellent input-high output-low emission", construct border food steady pattern and promote the long-term and stable development of the border areas.