As an important method for soil erosion monitoring, runoff plot plays a significant role in soil erosion and prediction model. How to measure the sediment concentration quickly and accurately in collecting tanks directly determines the scientific research in the law of soil erosion and the reliability of the soil erosion. Sampling after mixing is currently the most widely used in sediment concentration measurement. However，in some rocky and earthy regions such as Beijing mountain region, the traditional measurement method，which is widely used，can not get the precise value of sediment concentration. We use the depth profile sediment sampler, which is designed by Beijing normal university，to monitor the sediment concentration in the collecting tanks of the runoff plots. This research briefly discusses the using and rapid processing methods of laboratory samples.