It is very important to measure sediment concentration in flow-water on studying on soil erosion and soil and water conservation. A new portable instrument was adopted to measure the sediment concentration. The result showed that the sediment concentration in flow-water was in linear correlation with the mass of mixed liquor. Weight sensor can measure the sediment concentration. Adopting data fusion method based on statistics theory to handle measurement result can greatly improve the measurement accuracy and minimize the repeat error. The measurement accuracy is 0.63% and the repeat error is 0.49%. This measurement system provides a new, valid method to speed the procedure and correct the measurement of sediment concentration in flow-water.