Over many years,sediment in the Yellow River was generally dealt with the replacement method. This original method utilized sediment water separation method of siphon extraction to draw water by artificial labour. This method has large errors and the efficiency is low. Therefore, the author combined with the Yellow River hydrological reality and developed a "the automatically sediment separator". The analyzer uses a microcontroller to automatically seperate water and the sediment, and complete clear muddy water separation process automatically. The separator has been applied in the hydrological work of the Yellow River in Shandong. Practice has proved that the separator not only improve the accuracy of sediment tests, but also enhance the work efficiency and has a certain application value.