Abstract: Spring is a dry season in Yunnan, characterized by low precipitation and high drought vulnerability. Against the background of global warming, spring precipitation plays an increasingly important role in drought evolution and ecological agriculture in Yunnan. Based on monthly precipitation data from 160 stations compiled by the National Climate Center and monthly global reanalysis data from NCEP/NCAR, this study investigates the key winter precursors and their anomalous causes associated with the mitigation of drought in Yunnan during the spring of 2025, using Liang Kleeman information flow and composite analysis methods. The results indicate that the key winter precursors exhibited a positive anomaly with a pronounced increase from November to December 2024. This increase corresponds to a transition of the tropical oceans toward La Ni?a conditions, during which anomalous ascending motion over the western tropical Pacific expanded westward and northward, exerting influence over Yunnan and thereby favoring above-normal spring precipitation. Anomalous forcing over the western tropical Indian Ocean, western Pacific, central Pacific, and Atlantic Oceans can induce positive anomalies for the key winter precursors. Moreover, intra-seasonal variations in anomalous forcing extending from the western and eastern tropical Pacific to the Atlantic are likely the primary cause for the abrupt enhancement of the precursor in December. The positive anomaly of the key factor during pre-spring period of 2025 (November–December 2024) is mainly attributed to anomalous forcing from the tropical western Indian Ocean, while the key region responsible for the abrupt increase of the key precursor is located in the tropical central Pacific. This study identifies key winter precursors influencing spring precipitation, providing a physical basis for earlier warnings of potential drought and flood disasters in the region.