Through data collection and field sampling, the changes of topsoil nutrient contents in 1982, 2012, 2018 and 2022 in tobacco-fields in Binchuan County of Yunnan Province were analyzed, and soil integrated fertility index (IFI) and its spatial and temporal variation were quantitatively evaluated by using soil comprehensive evaluation method and Kriging interpolation. The results showed that in the past 40 years, soil pH (7.13-6.23) and organic matter content (35.30-27.71 g/kg) showed a decreasing trend, while the contents of Olsen-P (12.11-50.71 mg/kg) and available K (158.66-321.03 mg/kg) showed an increasing trend. No significant changes were found in alkali-hydrolyzale N content (119.03-117.00 mg/kg). Soil IFI (0.49-0.62) showed an increasing trend, with the average value increasing from 0.49 (Ⅲ level) in 1982 to 0.62 (Ⅱ level) in 2022, with the largest increase appeared in Pingchuan, Lawu, Zhoucheng and Binju towns. Current high fertility areas were mainly distributed in the north-east and south, while low fertility areas in the north-west. In addition, principal component analysis showed that the main internal factors affecting soil fertility changed from organic matter to available K. After 40 years of cultivation and management, soil fertility gradually increased from west to east and from north to south, but the non-equilibrium of nutrient indicators and spatial heterogeneity of soil fertility increased, and nitrogen and potassium fertilizers should be stabilized while phosphorus fertilizers should be reduced.