Abstract: The article makes emphatic research on the pyrite of the Ni-Mo poly-metal-element deposit in Zhongnancun of Zunyi in Guizhou and Sancha of Zhangjiajie in Hunan, the genesis of the ore deposit is hydrothermal exhalative sedimentary type. The average ratio of S/Fe of the pyrite sample is 2.0093-2.048, and the composition characteristic belongs to iron deficient type, indicating the forming temperature is low. The variant range of Co/Ni is 0.077-4.5, with the average as 2.197, so from the rate of Co/Ni we can judge the pyrite in this area is mainly hydrothermal genesis, and the mineralization resource is the thermal fluid of the hydrothermal exhalative sedimentary system. The composition diagram typomorphism indicates the pyrites of the high ω(Co+Ni)/ω(Fe) and ω(As+Se+Te)/ω(S) in the black rock series in this area occur in large amount, which is due to larger temperature variation range of the hydrothermal exhalative sedimentation, while not the product of the normal sedimentation. The S/Se rate is 950.8-1059.9, indicating the homogeneous extent of the productive environment is higher, and the temperature of the marine water is higher. From the Se/Te rate of Ni-Mo deposit in Zhongnancun (Se/Te=0.986), we also can conclude that the deposit is the genesis of thermal fluid. Research of the pyrite is of importance for the Ni-Mo deposits exploration in this area.