Combining with a domestic ship lock project,flow regime in chambers of two types of filling system through the head,in which setted simple energy dissipater and grid stilling chamber,was simulated by RNG κ-ε turbulence model and VOF method.Based on analysis of the simulation,a reasonable quantitative method was given.This simulation turned out that taking turbulence flow energy less than 0.02 m2/s2 as a quantitative indicator to determine the length of mitigative section during filling process meet the norms.