The invention discloses a fermentation tank for a sheep-manure organic fertilizer. The fermentation tank comprises a tank body, wherein the interior of the tank body is provided with a sieve plate used for placing a mixture; the tank body is divided into a fermentation chamber located above the sieve plate and a ventilation chamber located below the sieve plate through the sieve plate; the top part of the tank body is provided with an air cylinder which is provided with a ventilation pipe capable of downward stretching and reacting; the end part of the ventilation pipe is opened; the pipe wall of the ventilation pipe and the sieve plate are provided with a plurality of air holes with a pore size of 5 mm; the side wall of the fermentation chamber is provided with a material inlet and outlet door, a temperature measuring mouth and a sampling mouth; the top part of the fermentation chamber is provided with an air outlet; the ventilation chamber is externally connected with a vortex fan through a pipeline; a valve and a glass rotameter are arranged on the pipeline; and the glass rotameter is located between the valve and the ventilation chamber. By using the sheep manure fermented by using the fermentation tank provided by the invention, the seedling burnt situation may not be generated; meanwhile, the fermentation time is greatly shortened, and 20 to 23 days are only needed.