Abstract: Biological pre-enrichment of metals in the Pb-Zn-Ag polymetallic deposit of Qixiashan in Nanjing has been previously discussed. As biometallogenesis is a developing process together with geological processes, this paper mainly deals with migration and reduction by organic matter and organic fluid derived from bacteria and algae. The mineralization organisms and organic matter absorbed in ores in the deposit are systematically investigated, which reveals that they are al1 derived from bacteria and algae. Combining non-destructive analyses such as infrared and ultraviolet fluorescence microspectroscopy with destructive ones such as GC-MS, the authors focus on the hydrocarbon inclusions developed in the deposit. Series of biomarkers in the ore-forming fluid are identified, indicating their algal and bacterial sources. The basic analyses include the characteristics of organic matter in metallogenic fluid, the relationship among metallogenic elements and the distribution of metals in organic matter. Biometallogenesis other than pre-enrichment is thereby clarified to form an organism-organic matter-fluid (OOF) metallogenetic system.