Abstract: Sediment concentration is one of the main targets of the river and harbor physical model experiments. With narrow measuring range, large measurement error and low repeatability of faults, the existing sediment concentration technology restricts the test range and accuracy of physical model experiments. This paper introduces a new wireless real-time sediment concentration measuring instrument. It adopts photoelectric measuring principle, which realizes real-time online sediment concentration measurement by converting light signals into electrical signals. This paper mainly introduces the basic principle and hardware system design of the sediment concentration measuring instrument. The connection among transmission intensity, scattering intensity, optical power and sediment concentration is studied, and a method is proposed for measuring sediment concentration by combining transmission and 90° scattering light. In order to achieve the requirement that the relative error of the sediment content is less than 5%, the algorithm and implementation through multiple experimental studies are realized. The reliability of the newly developed instrument based on the uncertainty analysis method is analyzed. The experiment data show that the uncertainly of the sediment concentration measuring instrument is less than 0.4.