Abstract: The paper designs a diversion dilution experiment, trying to seek a simple way to diversion dilution and removing silt in a tideway of river. For the purpose of draining pollution water and removing silt, changing normal regulation of hydraulic structures to a collaborative means, the experiment was performed to diversion abundant clean water from Modaomen waterway in the Xijiang river to increase flow velocity and discharge in the Qianshanhe River to drain pollution water and remove silt in the River so as to improve the water quality of the rivers. The experiment results in good effect of draining pollution water and definitely water quality improvement. The main trough of riverbed was deepened by large discharge of the river while silted near the river mouth because the sand brought by current deposited near the mouth after closing the water gate. The variation of the silt quality relates much to silt, after experiment the silt quality was improved upriver where silt was removed and worsened in the deposited river mouth. This experiment proves to be quick effective and low-cost with good results.