Chromium-bearing sericite and chlorite occur in the Jinchang gold deposit of Mojiang County, Yunnan Province. Sericite is distributed extensively in pyritic chrome-phyllic rocks, pyritic siliceous rocks, pyritic chrome-mica and quartz veins, whereas chlorite is spread in quartz veins, siliceous rocks and pyritic chrome-phyllic rocks. Montmorillonite occurs in etched surrounding rocks, while kaolinite in gold-rich quartz veins. Based on 72 electron microprobe analytical data of the above minerals, the authors set up a series of compositional types related to the rock types. Studies show that all of the above layered chromium-high silicate minerals occur at the northernmost ends of different orts within Jinchang rock body. The SiO_2-Cr_2O_3 diagram of the chromium-aluminum mica reveals that different plot areas reflect specific genetic type features of source rocks. It is thus considered that the high-content spots of Si and Cr in chromium sericite series typical of the Jinchang gold deposit are basically attributed to the post-metamorphism hydrothermal fluid of the ultrabasic rock body.