In order to analyze the salt water movement characteritics in different depths of the salt collecting pit of the estuarine ship lock,we build a three-dimensional numerical model of the salt collecting pit for mitigation salt intrusion based on the species transport model and the LES turbulence model of the CFD software,and use the finite volume method discretization.Based on the test results of water tank for mitigation salt intrusion in the salt collecting pit,we verify the salt water movement pattern,salt water movement speed and vertical salinity distribution,and build a three-dimensional numerical model of different depths of salt collecting pit in estuarine ship lock.The results show that the mitigation salt intrusion effect of salt collecting pit is related to the depth.The distance of salt water intrusion increases with the depth of the salt collecting pit,but the salinity of the approach channel and salt-fresh water exchange rate decreases with the depth of the salt collecting pit.In general,the depth of the salt pit is directly proportional to the salty prevention effect.When the depth of the salt pit is greater than 12 m,the distance of saltwater intrusion is more than 515 m,the salinity of the approach channel is less than 0.23‰,and the salt-fresh water exchange rate is less than 50%.