To study the influence of the main tributaries in the lower reaches of the Jinsha River on the water temperature of the main stream, the measured data of flow and water temperature at 16 stations in the lower reaches of the Jinsha River were selected. The discharge proportions of each tributary in the lower reaches of the Jinsha River were statistically analyzed, and the water temperature change regularity of the main stream in the lower reaches of the Minjiang River, Jialing River, Wujiang River and other large tributaries after confluence was discussed. The results show that the Minjiang River, the Jialing River and the Wujiang River accounts for 18.8%, 14.2% and 10.79% of the flow discharge at the Yichang Station respectively. The change rule of water temperature downstream the main stream of Jinsha River is basically consistent with that of the tributaries, and the lag effect is gradually obvious with the increase of distance. The Minjiang River has the largest impact on the water temperature in the main stream, followed by the Jialing River and the Wujiang River. Through the linear function fitting method, the correlation coefficients of the temperature difference between the main stream and tributaries of the Minjiang River, the Jialing River and the Wujiang River and the temperature difference along the upstream and downstream of river confluences are 0.950 2, 0.884 5 and 0.786 3 respectively.