Chemical protection is one of the common used methods that protect and reinforce the historic relic being in severe danger,especially for the site composed of soil,stone and brick,etc in open environment.At present,the primary chemistry materials that have been tried for site protection are organic silicon compound and fluorine containing polymers,etc.These organic materials can play a certain role in the protection,but there are various defects.The soil,stone and brick are hydrophilic,and organic protecting materials are hydropholic. The frequent stress change on the interface of hydrophilic hydropholic makes protection layer desquamation.In this work,a multilayer chemical protection method that structured by hydrophilic external layer and hydropholic fundus layer was proposed and tested.Alkoxysilanes and fluoro rubber solution were selected as the external layer material,and polyacrylate and polyethylene glycol as the fundus layer material.From the experiments of decaying cycles that destructive factors such as moisture cycles,salt crystal,frost and fusion were included.It was found that the multilayer protection method obviously reduced the danger of interface breakage.Because there is a transition layer between hydropholic external layer and hydropholic relic materials that dispersed the stress of hydroscopic expantion strain and salt crystallize dilatant near interface.