The Shan-Shan Guildhall in Liaocheng, Shandong, was built in the eighth year of the Qianlong period. After several extensions and reconstructions, it has a compact layout and gorgeous decoration. It is a well-preserved excellentarchitectural complex in ancient guild halls. The guild hall has the functions of a temple and business hall. It is a witness to the commercial prosperity of the Grand Canal and has high artistic and cultural value. So far, the research on Shan-Shan Guildhall in Liaocheng mainly focuses on its architectural style, art aesthetics, etc. No scientific analysis of the manufacture techniques and materials used in its architectural color paintings exists. Here, 27 red pigments samples from the Shan-Shan Guildhall in Liaocheng were analyzed by microscopic observation, SEM-EDS, laser Raman, and infrared spectroscopy. It was found that the red pigments are Iron red (Fe2O3), vermilion (HgS), red lead (Pb3O4) and madder dyes (mainly C14H8O4 and C14H8O5). Multi-layer repainting techniques are commonly used, including applying new paint after remaking the ground battle, and the construction technique of ancient architectural color paintings that directly draws two layers of paint, such as “red lead base and vermilion cover”. Theresult is consistent with the documentary record. In addition, the technique of adding calcium and barium sulfates as modifiers to red pigments was also revealed. It is the first time to find madder dyes as architectural color painting pigments in our research, which strongly support the literature record of using organic dyes for architectural color paintings in the Qing Dynasty. Previous studies on the analysis of madder dyes in ancient cultural relics mainly focused on archaeological textiles, mostly using mass spectrometry, which requires expensiveequipment and complex sample pretreatment. In our work, the laser Raman spectroscopy was used to perform convenient and non-destructive analysis for madder dyes in ancient architectural color paintings, and good identification results were obtained. It will provide an important technical reference for the scientific analysis of organic dyes in ancient architectural color paintings.