Abstract: Taking the Bijiashan antimony deposit as the research object, we reveal the source and nature of ore-forming fluid using ICP-MS analysis of stibnite based on the fine dissection of ore deposits. The REE patterns of stibnite show enrichment of LREE with the intense fractionation, with obvious Tb and Dy positive anomaly and Eu positive anomaly, which is similar with the REE patterns of the Himalayan alkali-rich porphyry. Furthermore, the characteristics of strongly Sr and Ba positive anomaly in the trace element of stibnite, is consistent with that of the Himalayan alkali-rich porphyry. The Y/Ho ratios of stibnite increase along with the increase of altitude and degree of oxidation. The Y/Ho ratios of stibnite with high degree of oxidation is similar with the Y/Ho ratios of sea water and the Y/Ho ratios of stibnite with low degree of oxidation is similar with the Y/Ho ratios of the Lianhuashan alkali-rich porphyry, which suggests that ore-forming fluid may be from the mixture of magmas and atmospheric water and that is also supported by H-O isotope study. Isotope analysis reveals that Pb is from multiple sources and S of stibnite is a mixture of biological sulfur and magmatic sulfur. Results display that the deposit controlled by interformational fracture zone is an epithermal deposit which formed in distal volcanic settings.