[Objective] The long-term trend, staged, abrupt, and multi-scale periodic variations of the discharge from the Yangtze River into the sea were analyzed in the past 150 years to provide theoretical support for revealing the long-term variation characteristics of the flow of the Yangtze River into the sea.[Methods] Based on the hydrological data of the Hankou station in the Yangtze River, this paper reconstructed the runoff series of the Datong Station, Yangtze River from 1865 to 2014, by using the regression model derived from Hankou station and Datong station, and made use of a variety of methods to carry out multi-scale analysis.[Results] The discharges from Yangtze River in nearly 150 years had an average flow of 29 432 m³/s, and had a coefficient of variation of 14.72%. The trend analysis showed that the discharges from Yangtze River in the past 150 years showed a decreasing trend with rate of -23.7 m³/(s·a)(p < 0.01) per year. Although, the periodic analysis showed that the change of the series had fluctuation characteristic. Two obvious different stages were recognized and it was separated at 1955. From 1865 to 1955, it was at a rising stage; from 1955 to 2014, it was at a descending stage. Abrupt analysis showed that the series had an abrupt point in 1940s, around which the water flow changed from wet period into dry term. The multi-scale periodic analysis showed that the series were obvious non-linear and nonstationary, with 150 years and 60 years of long-term trends, and with 34 years, 22 years, 3 to 7 years of high frequency oscillation cycles. Among of the cycles, the most obvious was 22-year one, which can be tested at 99% confidence level.[Conclusion] In the past 150 years, the flow of Yangtze River into the sea had been in a downward trend, especially since 1955, it declined significantly. The variation of precipitation in the Yangtze River basin was an important factor that affected the runoff in the Yangtze River.