According to the waterway planning of Oujiang river,the capability of Waixiong ship lock is to be 500 t ships from the original 300 t ones.It is proposed to set a grid stilling chamber in the filling and emptying system to make the effective length and mooring condition of a 500 t ship meet the requirements in Waixiong ship lock,and a 1:20 overall physical model experiment is carried out.The result proves that the grid stilling chamber can not only shorten the length of mitigative section in the ship lock,but also play a very good role in improving the flow regime in ship lock,which makes the filling time and mooring condition of the ship meet the design requirements and norms.The layout of grid stilling chamber is adaptable to the centralized water conveyance system.