Hancheng Dayu temple was built in 1301 and rebuilt in 1579. The top of the caisson shrine was painted with a total of 168 painted cells. The colors of the painted flowers and birds are very bright. The paintings have high historical and cultural value.In recent years, due to environmental effects, a large area of the painting suffered from severe deterioration including peeling, pollution, warping, bubbling, tearing, embrittlement and other diseases. The caisson itself was in danger of destruction. Without rescue repair, the caisson painting might disappear forever.Based on research and disease analysis, deacidification and pigment reinforcement methods using appropriate conservation materials were developed. A simulation paper was treated and the intensity and folding endurance characteristics of the simulated paper sample before and after reinforcement, aging and deacidification were tested. The results showed that the deacidification agent is capable of maintaining the original appearance of the caisson drawing;that the color and texture of the case, and that the protection of the physical properties of each caisson drawing was improved greatly after the treatment. The deacidification and reinforcement greatly extended the life of the caisson. This research provides a scientific basis for repairing the painted Hancheng Dayu Temple caisson.