Abstract: Hercynian granite is found developed in Haoyao'erhudong gold deposit, a low-intermediate hydrothermal deposit with low-grade ultra-large reserves. Analysis on the granite has shown that the ratio of SiO₂ ranges from 71.5% to 73.07%, and the ratio of Na₂O/K₂O ranges from 0.59 to 0.67 with an average value of 0.64, thus the granite belongs to high-K calc-alkaline series. According to Hark diagram, the content of each element is obviously in line with the variation tendency of SiO₂, to express the characteristics of I-type granite. The content of Mg# ranges from 39 to 49, and its average of 43 is similar to the average value(45.36) of lower crust granulite. The value of ∑REE from 72.64×10^-6 to 132.6×10^-6 signifies a low content of rare earth. The ratio of (La/Yb)_<i>N ranges from 12.99 to 34.13, revealing biggish fractionation between LREE and HREE. The distribution curve on REE spider chart goes right. The ratio of Ba/Th ranges from 133.93 to 178.93, indicating less influence on the underthrust plate. The content of δEu varies from 0.52 to 0.96, with an average of 0.75, indicating negative Eu anomaly from intermediate to a lower level. According to some other geochemical features, it is considered that the ore body is high-K Calc-alkaline I-type granite formed in post-collision environment.