”Sancai dingwei tu (Illustrated Pantheon of the Three Spheres)” produced by Zhang Shangying (1043-1121) is one of the earliest extant paintings of the Daoist pantheon and is considered as a precious document on Daoist art and theology of the Song dynasty. However, the only extant version preserved in the Daoist Canon of the Ming dynasty is incomplete and there are discrepancies between its images and text. Hence, how it should be understood remains debatable. The aims of this paper are twofold. First, it seeks to assess the validity of the present version of the ”Sancai dingwei tu” by analyzing the images of the deities, the structure of the pantheon and its underlying cosmology in relation to the specific political background and the probable intentions of its production. Second, based on the case study of the ”Sancai dingwei tu”, this paper considers the extent to which illustrations of Song dynasty scriptures preserved in the Ming Daoist Canon are faithful to their Song originals and can be treated as Song dynasty visual materials. This paper will argue that the structure of the pantheon as shown in the ”Sancai dingwei tu” is based on the cosmology of the ”Duren jing (Book of Salvation)”. In the painting, the relationship between the three main deities, Tianzhen huangren, Lingbao zun and the Holy Ancestor (Shengzu), are established through the integration of different Daoist traditions. The main purpose of the painting is to establish a pantheon that represented the union of various Daoist sects and the state, meanwhile highlighted the characteristic of the Holy Ancestor of the Zhao ruling family that brought salvation to mankind and prosperity to the state. The ”Sancai dingwei tu” expresses these core ideas primarily through images and should be seen as a product of the craze for auspicious images in Northern Song times.