The main deposition in approach channel of ship lock is caused by density flow with the characteristics of long distance and large total volume.If the deposition is not treated in time,the navigable depth will be reduced to influence on the navigation security.Due to the limited materials,it has great value for make dredging scheme to calculate the deposition volume by the existing formulas.This paper advances the improved sediment concentration correction formula along river considering the increase of clean water in density flow.The calculated results by the proposed formula matches the measured data well,which provides a new way for the density flow deposition calculation.