We Collected measured data and analyzed the variation characteristics of the hydrological elements in the Yangtze River Estuary，such as the discharge of Datong station and the velocity of the North Passage middle station from 2016 to 2019.The results show that：1）The annual total runoff volume of Datong Station in recent four years is close to the average of previous years. The maximum monthly average flow occurs from July to August，and the minimum occurs from October to February. 2）The monthly averages of high and low tide，tidal level and tidal range in the North Passage middle station have a single-peak distribution during the year，and the peak occurs from August to October. The changing trends of the 3 different stations are basically the same. The monthly average tide level in the east of the South Passage station is the highest and the tidal range is the largest. 3）The monthly mean value of the ebb current is larger than that of the flood current in the North Passage middle station and reaches the peak from June to August. The flood current reaches the trough from June to August. The monthly average velocity of ebb tide is larger than that of flood tide. The average monthly velocity of flood tide reaches its minimum in July. The monthly average duration of low tide is larger than high tide and reaches the peak form June to August. 4）The water temperature in the North Passage middle station has an obvious change during the year. The monthly average temperature in August can reach 29.96 ℃，and the monthly average temperature in February is 7.51 ℃. 5）The monthly average effective wave height and period of the east of the South Passage station，Niupijiao and Yangtze River Estuary are basically the same. From the perspective of annual distribution，the effective wave height changes greatly and the wave period changes little. The effective wave height and wave period of the Yangtze River Estuary station are higher than those of the other two stations. The difference between the significant wave height and wave period of the east of the South Passage station and Niupijiao is small. The total wave energy of the three stations is the smallest at the east of the South Passage station and the largest at the Yangtze River Estuary.