[Objective] The level of grassland carrying capacity affects the sustainability of grassland utilization and the security of grassland ecosystems. The carrying capacity of grassland resources in Xilingol League, Inner Mongolia (an important ecological barrier in the north) was analyed in order to provide a scientific basis for the regional ecological security and sustainable use of grassland and the construction of ecological civilization. [Methods] We analyzed and evaluated the status of grassland resource carrying capacity, ecological deficit (ED)/remainder (ER), and ecological pressure index of Xilingol League of Inner Mongolia based on a three-dimensional ecological footprint model. We used land use and other relevant data in 2013, 2015, 2018, and 2020. [Results] ① The ecological footprint continued to be higher than the ecological carrying capacity. The total ecological footprint and total ecological carrying capacity showed a trend of first increasing and then decreasing, decreasing by 2.76% and 7.35%, respectively, over 7 years. The change rates of per capita ecological footprint and per capita carrying capacity over 7 years were -9.62% and -13.19%, respectively. The ecological footprint decreased from east to west, and the ecological carrying capacity in the east and north was higher than that in the west and south. ② The ecological footprint depth first increased and then decreased, with an overall increase of 4.95%, which was greater than 1. The grassland ecosystem remained in an ecological deficit state for many years, indicating that the grassland ecosystem was unsustainable and unhealthy. ③ The results of ecological profit and loss and ecological pressure index reflecting the ecological security of grassland showed that ER/ED was less than 0 and the ecological pressure index was greater than 1 in the study area during the four periods of the study. The ecological carrying capacity of grassland has been continuously overloaded for many years, and the ecological security and stability have continued to decrease. [Conclusion] The arid and semi-arid geographic location of Xilingol League and its resource endowment, combined with high-intensity human economic and social activities, have led to a reduction in the ecological carrying capacity of the grasslands of Xilingol League, and the ecology of this area is in an extremely insecure state.