<p>The processes of desertification and land degradation have accelerated in many regions worldwide. Focusing on three typical sady areas in northern China, the impacts of human activities on desertification and land productivity were investigated. A regional land productivity estimation model was employed to evaluate land productivity in each sandy area from 2000 to 2019. Empirical Orthogonal Function analysis and panel regression models were then applied to examine the spatiotemporal variation characteristics and their relationships with human activities. The results indicate that: (1) the land productivity of the Hunshandake desert declined significantly after 2013, whereas the Songnen and Badain Jaran deserts exhibited cyclical fluctuations; (2) over the past two decades, the intensity of human activities in the Songnen desert has continuously increased, while showing the opposite trend in the Badain Jaran desert; in the Hunshandake desert, human activity intensity remained largely stable before 2013 but increased markedly thereafter; and (3) the suppressive effect of human activities on land productivity was most pronounced in semi-arid regions. In contrast, arid regions were mainly influenced by natural conditions with relatively weak human activity, while semi-humid regions could mitigate this suppressive effect due to their high levels of development and management capabilities. These findings further confirm the adverse effects of human activities on desertification processes, as well as the vulnerability of land productivity in transitional zones between arid and humid climates.</p>