Abstract: To gain a deeper understanding of the short-term water temperature variations and influencing factors in the lower reaches of the Jinsha River, and to quantify their impact, we established a multiple regression model to quantify the influence of upstream water temperature, tributary water temperature, and air temperature on downstream water temperature.The research information includes the water temperature data of the mainstream and tributaries from August 1,2022,to July 31,2023,in the section from Xiangjiaba Hydrological Station to Qingxichang Hydrological Station in the lower reaches of the Jinsha River and the air temperature data from nearby meteorological stations.The results show that:(1) Upstream water temperature is the primary factor affecting downstream water temperature, with an influence ranging from a minimum of 52.7% to nearly 100%;(2) The water temperature from tributaries flowing into various river sections significantly impacts downstream water temperature.For example, the tributaries of the Minjiang River, Jialing River, and Wujiang River notably influence downstream water temperatures, with the Minjiang tributary affecting the water temperature at the Lizhuang Water Level Station by up to 45.1%;(3) Air temperature has a relatively weak short-term effect on downstream water temperature, ranging from only 0.4% to 2.2%,which is significantly lower than the influence of upstream water temperature and tributary water temperature.