The invention discloses a gas-liquid mixture conveying pump for biological fermentation tanks, which comprises a motor (1), a base (4), a mechanical sealing seat (6), a liquid inlet pipe (11), a fermentation tank body (18), a gas inlet pipe (19), a gland (22), a gas-liquid mixture conveying impeller (25) and a bracket (26); and the pump is characterized in that the base (4) is arranged at the bottom of the fermentation tank body (18), the mechanical sealing seat (6) is arranged in the base (4), the bracket (26) is arranged in the mechanical sealing seat (6), a main shaft (27) is arranged in the middle of the bracket (26) in a penetrating mode, the gas-liquid mixture conveying impeller (25) is sleeved on the main shaft (27), and the liquid inlet pipe (11) and the gas inlet pipe (19) are communicated with a mixing chamber (14). According to the technical scheme of the invention, the pump disclosed by the invention has the following beneficial effects that the pump is simple in structure, small in volume, safe and reliable, and convenient for installation, use and maintenance; and the manufacturing cost is much lower than that of a traditional mechanical stirring and air-compressor gas supply system.