Abstract: The main reason for the corrosion of SG heat transfer tube is the deposition of sludge particles on the tube bundle.Numerical simulation was used to study the deposition characteristics of the sludge particles on the tube bundle,and the deposition characteristics of various size sludge particles on the different locations of the tube bundle.Studies have shown that low flow rate and backflow were the main reasons for the retention of sludge particles in the tube bundles.When the particle size is larger,the deposition of sludge particles in the bottom plate,flow distribution plate and support plate is more dispersed.With the particle size is decreased,more sludge particles are deposited on the central of the bottom plate,and on the barrel of the flow distribution plate,and on the central of the support plate.