Abstract: "Shetaicui" jade is named after the location of its origin,the Dashetai area of Wulateqian Qi,Bayan Nur city,Inner Mongolia.The mineral components,chemical compositions,microstructure and colour-causing mechanism of white,green,yellow,purple series of "Shetaicui" jade are studied with the help of polarizing microscope,X-ray powder diffraction(XRD),electron microprobe.The results show that the mineral component is slightly different among those different colours of "Shetaicui" jade.The typical mineral component is quartz(about 80%) in most colours of the "Shetaicui" jade,except for the white one,which contains plenty of dolomite(higher than 60%).And the secondary mineral components in "Shetaicui" jade are mica,calcite,feldspar,hematite,pyrophyllite,illite,kaolinite.The colour of the green "Shetaicui" jade is changed to red under Charles filter,which is caused mainly by chromium mica.So,the green "Shetaicui" jade belongs to aventurine.In addition,the white "Shetaicui" jade is one of the dolomite jade,and the yellow and other coloured ones belong to quartzite jade.