This study explores the polychrome interior design of the Song-dynasty main hall of Kaihua temple located in Gaoping county, Shanxi province. Based on on-site investigation and high-resolution digital data acquisition carried out from 2015 to 2017, the paper documents the current state of decoration of architectural components and of wall paintings. After identifying the basic forms of decoration, the paper compares them with the specifications on pattern and color recorded in Yingzao fashi. Finally, the paper restores the original colorful appearance of the main hall to reconstruct the effffect of the painted interior as a whole.