The invention relates to a material discharging mechanism of a storage tank. The material discharging mechanism is arranged in the storage tank and connected with a storage tank feeding pipe. An anti-separation device comprises a drum-shaped cavity and a falling pipe connected to the lower portion of the drum-shaped cavity. The inner wall of the drum-shaped cavity is smooth. A plurality of falling ports are formed in the two side pipe walls of the falling pipe. The falling ports extend inwards into the falling pipe. A bend is arranged between the drum-shaped cavity and the storage tank feeding pipe, and the bending angle of the bend is 45 degrees. The material discharging mechanism is simple in structure, low in energy consumption, capable of preventing hard drying condensation and convenient to maintain. According to the material discharging mechanism, the anti-separation device is additionally arranged on the top of a feeding port, the falling pipe is welded to an opening in the lower side of the material discharging mechanism, the openings are formed in the two sides of the falling pipe in a segmented manner, and volute circulation is achieved for dry-mixed mortar in the drum-shaped cavity through airflow of a pneumatic pump till the lower side of the anti-separation device naturally falls down in a segmented manner; and accordingly, the using effect of dry-mixed pre-mixed mortar is guaranteed, overflow of cement dust from an air outlet pipeline is reduced as well, and the environment is protected.