The use of PS for anti-efflorescence treatment of large-scale earth sites during the past twenty years is summarized.PS treatment has been found to be an effective technique.The technique includes surface spraying infiltration and trickle infiltration.These two methods can be applied together or separately.Surface spraying infiltration involves spraying of a PS solution directly on the wall,which applies the solution to the thin weathered layer in the walls of adequate strength.Trickle infiltration is accomplished by drilling small holes in the wall and injecting the PS solution by means of a small rubber tube or syringe needle.This method is suitable for walls with thick weathered layers and low strength.After PS treatment,the enhanced wall changes color slightly.The color can be restored to get the original look.A number of previous examples and follow-up examinations have proved the technique to be effective and worthy of applying in other projects.