Abstract: Due to insufficient methods used in accurately measuring fluvial suspended sediment concentration (SSC), it is proposed that the Yangtze sediment flux entering the sea in the history has been devalued in general. This paper uses the sediment rating curve to simulate the sediment flux on the basis of on-site measured SSC and published values from the Datong Hydrological Gauging Station for the past 40 years. The simulated result demonstrates that in addition to the value of 1950s that is somewhat lower than the published one, the yearly sediment flux reaches about (5~9)×10⁸ t for 1960s and (5~6.4)×10⁸ t for 1970s. The simulated value declines slightly during 1980s. These keep well with the general situation of vegetation conservation in the upper Yangtze sediment source area, where the conservation was somewhat good in 1950s, and subsequent deforestation prevailed in 1960s. After then, the land conservation was improved in 1970s and 1980s.