[Objective] In order to deeply understand the kind of anaerobic bacteria species and the impact of quantity change on Maotai-flavor liquor.[Methods] The lower fermented grains in the process of Maotai-flavor liquor were taken as the material. Quantity of anaerobic bacteria were conducted by plate count method and dynmic change of the amount of anaerobic bacteria and physical indexes were analyzed. The anaerobic bacteria were chosen to check through the SEM, combining with physiological and molecular experiments. [Results] Four strains of anaerobic bacteria were identified in fermented grains and anaerobic bacteria are respectively Clotridium xylanolyticum, Clostridium amylolyticum, Clostridium subterminate and Clostridium sartagoforme.