The Weishan Third Line Ship Lock Project is located on the main channel of the Grand Canal Link and the eastern water transmission line of the South to North Water Diversion Project,and needs to balance the goals of efficient navigation and water conservation.To the problem of calculating the plane scale of lock chamber and the capacity of ship lock chamber and the water consumption of lock chamber,based on the analysis of the ship-to-ship ratio and ship-type scale in the design level year,this paper puts forward different lock chamber plane scale schemes according to the main ship-type scale,and carries out the calculation of the lock carrying capacity and water consumption to obtain the quantitative relationship between lock carrying capacity,water consumption and lock chamber plane scale.The conclusion is that the passing capacity of Weishan Third Line Ship Lock increases with the increase of the lock chamber plane scale,but the increase is different.The water consumption does not increase with the increase of the lock chamber plane scale.Therefor,it is necessary to conduct a plane scale demonstration of the lock chamber.The plane size of the lock chamber for Weishan Third Line Ship Lock Project should be 34 m × 280 m.The method for determining the plane scale of the lock chamber in the Weishan Third Line Ship Lock Project has positive reference significance for similar engineering construction and standard revision.