Abstract: With the development of Maweishan pyrite deposit，it is found that pyrite ore bodies in the deposit are strictly controlled by strata，and most of them are layered-like，while there are a large number of colloidal pyrite in pyrite ore bodies. In order to determine the genesis of Maweishan pyrite deposit and the formation mechanism of colloidal pyrite，the geological characteristics of Maweishan pyrite deposit and the mineral characteristics of pyrite ore were studied，and the mineral characteristics of colloidal pyrite ore in Xinqiao pyrite deposit in Tongling were compared. It is determined that pyrite orebodies are generally developed in the strata of Huanglong and Chuanshan Formation in the upper Carboniferous system，and the banded fissures of colloidal pyrite are filled with chalcopyrite，and pyrite and sphalerite are wrapped around them. By comparing the mineral characteristics and metallogenic conditions of colloidal pyrite with those of Xinqiao pyrite in Tongling，it is speculated that the genesis of colloidal pyrite in Maweishan pyrite deposit is similar to that of Xinqiao pyrite，and it is formed by biochemical deposition. It is proved that Maweishan pyrite deposit has three metallogenic stages: primary sedimentary stage，magma-hydrothermal stage and supergene weathering stage，and colloidal pyrite was formed in the primary sedimentary stage at the early metallogenic stage.

Key words: pyrite deposit, geological feature, colloidal pyrite, biochemical deposition