The utility model discloses a continuous monitoring anaerobic fermentation tank of a sampling loop, which is characterized by comprising a fermentation tank main body, a monitoring system sampling device, a stirring element, a heating device and a gas storage device, wherein the bottom of the fermentation tank is provided with a heating element, and the top of the tank body is provided with a hemispheroid inner film of a gas storage cabinet with expanding and contracting functions, and an outer film of the gas storage cabinet; and a submersible mixer is arranged at the liquid surface position of the tank body, and the axis of the mixer is arranged in a mode of facing to the liquid surface and being arranged obliquely downwards; and monitoring sampling systems are arranged on the top and the outer wall of the tank and a sampling backflow pipeline, therefore, a hardware platform can be provided for continuous monitoring on the fermentation and methane generating process, the methane fermentation tank during the anaerobic fermentation process can be continuously monitored, and operators in a factory can monitor dynamic change of the methane generating process on line, and master the microbial fermentation process, so that high-efficient running and managing of the fermentation tank can be realized.