 This study investigates the spatiotemporal distribution and variations of soil moisture, SM, on the Mongolian plateau from 1982 to 2018 using for-gridded SM datasets, validating their reliability and uncertainties through observed SM from monitoring stations and the three-cornered HAT method. The results show that all four products underestimated SM in the region at different levels, with ERA interim SM performing best. The surface SM exhibits a decreasing trend of minus 0.0004 to minus 0.0008M3.M3 decade in the warm season, with the greatest decreases occurring in the summer season. Precipitation change plays a more important role in explaining variations of SM than temperature. The findings will benefit our understanding of climate change effects and ecological systems protection in the region. We are article.tv, links in the description below.