Purple “Shanzilai stone” is a kind of Shoushan stone, is a clay jade composed of layered silicate minerals. Its surface weathering for yellow, internal purple, belongs to the seal stone in the relatively rare color varieties. The appearance characteristics were studied by conventional gemstone microscope. The mineral composition, chemical composition and geochemical characteristics were studied by X-ray powder crystal diffractometer, microscopic laser Raman spectrometer, scanning electron microscope and laser denudation plasma mass spectrometer. The color origin was studied by whole rock chemical analysis, UV-visible spectrophotometer and SPSS analysis model. The results show that the main mineral of the Purple“Shanzilai stone”is Illite, and the secondary minerals are Monazite, Gorceixite, Hematite and Barite. The indicator data of REE show enrichment of LREE elements and deficit of HREE, indicating that the origin of the minerals is related to reduced acidic hydrothermal alteration. There is a positive correlation between the purple color and manganese content in Illite. The different types, distribution characteristics and formation temperatures of the main minerals and secondary minerals in Purple “Shanzilai stone” indicate that hydrothermal intrusion occurred several times in the late mineralization period, so the formation process of Purple “Shanzilai stone” is consistent with the metallogenic law in Shoushan area.