Baiguoyuan silver-vanadium deposit is generally thought to be of sedimentary-diagenetic origin. Based on the characteristics of barites, it is suggested that hydrothermal transformation has been involved in mineralization. The barites in black shale can be grouped into irregular ones which were formed during early diagenesis and tabular ones which were formed during late diagenesis. The tabular barites are replaced by pyrite and have formed a regular girdle around them. PIXE analysis states that Ag is greatly concentrated in pyrite replacement girdle. The girdle is the product of hydrothermal transformation. The transformation is one of the main mineralization stages of Baiguoyuan deposit. Based on the characteristics of barites, it is suggested that hydrothermal transformation has been involved in mineralization. The barites in black shale can be grouped into irregular ones which were formed during early diagenesis and tabular ones which were formed during late diagenesis. The tabular barites are replaced by pyrite and have formed a regular girdle around them. PIXE analysis states that Ag is greatly concentrated in pyrite replacement girdle. The girdle is the product of hydrothermal transformation. The transformation is one of the main mineralization stages of Baiguoyuan deposit.