The invention belongs to the technical field of fermentation equipment, and discloses a ventilation device of a Pu'er tea solid fermenter. The ventilation device comprises gas cylinders arranged at the two ends of the bottom of the fermenter, gas guiding flanges and gas spraying assemblies; ventilation ports are formed in the side walls of the two ends of the fermenter and detachably connected with the gas guiding flanges; the gas cylinders are used for driving the gas guiding flanges to stretch out and draw back so that gas guiding through holes between gas cylinder push rods and the gas guiding flanges can be connected with or separated from the ventilation ports to achieve ventilation or stop ventilation; moreover, ventilation pipes are uniformly arranged at the junctions of the bottomin the fermenter and the ventilation ports. According to the ventilation device, by improving the composition and setting mode of all components in the ventilation device and adopting the gas cylinders for driving the gas guiding flanges to stretch out and draw back, the detachable connection between the gas guiding flanges and the ventilation ports in the side walls of the two ends of the fermenter is formed, the ventilation uniformity in the fermenter can be effectively improved, and the gas utilization rate can be effectively increased.