Abstract: Part of a gold deposit belongs to altered type gold deposit. The gold bearing alteration zone is composed of sericite, silicification and pyritization caused by hydrothermal alteration of granite. Most of the ore bodies are hosted in pyrite sericite and some in pyrite sericite granite. Using optical microscope, mineral analysis system (BPMA), scanning electron microscope and energy spectrum, the process mineralogical characteristics of minerals were analyzed. It was found that sulfide ore was the main ore and the depth of oxidation zone was very shallow. The gold grade is 5.23 g/t. The main gold minerals are natural gold and silver gold. The main metal minerals are pyrite, pyrrhotite, galena, chalcopyrite, sphalerite and other sulfide minerals and magnetite and other oxide minerals. Gangue minerals mainly include quartz, sericite, feldspar, etc. The size of gold is fine, all of which are below 37 μm. According to the occurrence state of gold minerals, the content of gold bearing minerals existing in monomer form and coexisting with pyrite is 83.18%, which is easy to recover; the content of gold minerals associated with sericite, quartz and magnetite is 16.82%, which is the main reason for the low gold recovery rate in flotation process.