Abstract: Based on the monitoring data of summer hypoxia off the Yangtze River Estuary from 2010 to 2017, this paper analyzed the interannual variation characteristics of the location and range of summer hypoxia off the Yangtze River Estuary, and discussed influencing factors of the annual variation of hypoxia. The results showed that the hypoxia existed almost every year in the sea area adjacent to the location of 123°E, 31°N off the Yangtze River Estuary. The hypoxia would reach the sea area north of 32°N off the Yangtze River Estuary when the hypoxia had gotten severely; the changes of the hypoxia range off the Yangtze River Estuary over the years were greatly affected by the Taiwan Warm Current, when the Taiwan Warm Current was strong, the hypoxia area was larger and its location was farther north off the Yangtze River Estuary; the changes of the hydrodynamic in the hypoxia area caused by the Taiwan Warm Current. The low dissolved oxygen and high nutrient characteristics of the sub-surface water of the Kuroshio in the bottom of the Taiwan Warm Current were important factors affecting the reoxygenation and oxygen consumption in the bottom water of the hypoxia area, the intensity of the Taiwan Warm Current and the characteristics of the subsurface water of the bottom Kuroshio played important roles in the interannual variation of summer hypoxia off the Yangtze River Estuary.