基于内蒙古45个气象站点1980—2019年日均地表温度数据、结合中国第一代全球陆面再分析产品（CRA）数据以及NDVI数据，利用趋势分析法、相关性分析法和灰色关联度，对内蒙古近40 a地表冻融指数时空变化特征及驱动因素进行分析。研究表明：(1) SFI（地表冻结指数）年均值的空间分布特征表现出自西南向东北递增的规律，STI（地表融化指数）则反之，纬度是影响地表冻融指数空间分布的关键因子。研究期间SFI和STI分别呈现出显著下降和上升趋势，多年变化范围分别为956.1~1848.3 ℃·d和3717.6~4442.3 ℃·d，变化率分别为-156.4 ℃·d·（10a）^-1和152.4 ℃·d·（10a）^-1；与季节冻土区相比，多年冻土区的冻融指数对气候变暖的响应更加敏感。(2) 研究区近40 a土壤表层含水量、降水量、NDVI呈增加趋势，雪深呈减少趋势，但年际变化表现出不同的空间差异性，多年冻土区呈暖干化发展趋势，季节冻土区呈暖湿化发展趋势。(3) 地表冻融指数与影响因素以负相关关系为主，SFI与影响因素在多年冻土区大部呈正相关关系，在季节冻土区大部呈负相关关系，STI则反之。内蒙古地表冻融指数变化受影响因素共同驱动，0.4 m土壤含水量是影响SFI变化的主导因素，NDVI是影响STI变化的主导因素。研究结果可为内蒙古冻土退化、农牧业生产等提供科学的参考。

Using the trend analysis, correlation analysis and gray correlation, the spatial and temporal variation characteristics and driving factors of the surface freezing index (SFI) and surface thawing index (STI) in Inner Mongolia over the past 40 years were analyzed based on the daily average surface temperature data of 45 meteorological stations in Inner Mongolia from 1980 to 2019, combined with China’s first-generation global land surface reanalysis product (CRA) data and the NDVI data. The study shows that the following: (1) the spatial distribution of annual mean values of the SFI had an increasing pattern from southwest to northeast, while the STI had the opposite pattern, and latitude was the key factor affecting the spatial distribution of the SFI and STI. The SFI and STI showed significant decreasing and increasing trends during the study period, with multi-year variations ranging from 956.1 to 1848.3 ℃·d and 3717.6 to 4442.3 ℃·d, respectively, and rates of change of -156.4 ℃·d·（10a）^-1 and 152.4 ℃·d·（10a）^-1. Compared with the seasonal permafrost zone, the freeze-thaw index in the multi-year permafrost zone was more sensitive to climate warming. (2) The soil SW content, precipitation, and NDVI in the study area showed an increasing trend, and the snow depth showed a decreasing trend over the last 40 years. However, the interannual variation showed different spatial variability, with a warm-dry trend in the multi-year permafrost area and a warm-wet trend in the seasonal permafrost area. The SFI, STI, and influencing factors are mainly negatively correlated. The SFI and the influencing factors were mostly positively correlated in the multi-year permafrost area and mostly negatively correlated in the seasonal permafrost area. The STI was the opposite of the SFI. The change of the SFI and STI in Inner Mongolia was driven by a combination of influencing factors, while 0.4 m of soil water content was the dominant factor affecting the change of the SFI, and NDVI was the dominant factor affecting the change of the STI. The results provide valuable references for permafrost degradation and the production of agriculture and livestock in Inner Mongolia.