Abstract: Gamma ray attenuation and water level measuring methods were used to design an integrated automated system to determine the dynamic state of sediment concentration and flow rate in runoff. The system makes possible the real time, high frequency, precision and simultaneous measurements of sediment concentration and flow rate, as well as the storage, retrieve and long distance transmission of measured data. The system consists of four subsystems: the automated sampling, automated measuring and acquisition, data analysis/output/retrieve and operation/control. Laboratory application experiments and tests of the integrated system indicate that the system has such unique capabilities as short time for high precision measurements, and fast transmission of logged data. The system is so designed that it can be used not only for measuring sediment concentration and flow rate in the laboratory experiments of soil erosion study, but also for field research and for on site long term monitoring of soil and water loss from runoff plots.