This study was aimed at the relationship between anaerobes and clinical infection. Aerobic and anaerobic bacterial culture was performed for 436 specimens of clinical infection. The incidence of anaerobic bacteria isolates and predominant species were analyzed. The results showed that the incidence of anaerobic isolates was 88.3% (385/436), the main predeminoue species were Gram negative nonsporeforming anaerobic rods (Bacteroids, Prevotella and Porphyromonas) and peptostreptococcus. The endogenous infection, caused by anaerobic microflora of human body as the main pathogens, and the mixed bacterial infection are the most common feature of human clinical anaerobic infections.