Based on the principle of “wood bone and clay body” used to make clay sculptures found in the Dunhuang grottoes and the methods of testing adhesive strength of coatings and binders, a fixture has been developed for directly evaluating the surface adhesive effectiveness of wall painting conservation materials at the interface between the paint layer and the plaster layer and between the plaster layers. The invention of this fixture has solved such problems as adhesion interface mismatch, lack of objective data, poor application and low efficiency in evaluation of the surface adhesive effectiveness of the conservation materials. In our study, we determined the adhesive strength of six commonly-used conservation materials with mass concentrations of 5%; the sequence from the strongest to the weakest is as follows:pure acrylic emulsion＞PVA-1788＞PVAC emulsion＞silicone-acrylic emulsion＞gelatin (Paraloid b-72). According to the experimental data, it is proposed that selecting conservation materials and working concentrations should consider the proximity to the adhesiveness of original binding materials (gelatin), the closer the better.