The utility model discloses a semi -automatic second grade screening sand machine, including two -stage screening sand mechanism, in the first order screening sand mechanism, motor no. 1 drives big bevel gear through reduction gear no. 1 and rotates, it rotates to drive little bevel gear with the coaxial big bevel gear of ring flange, little bevel gear drives the stirring rod and rotates, the upper end of stirring rod is blocked by two dogs, the lower extreme sets up in the gross porosity screen cloth, the gross porosity screen cloth inlays outside in the cask, outer cask is installed on screening sand machine support frame, in the screening sand mechanism of the second level, motor no. 2 drives the eccentric wheel through reduction gear no. 2 and is rotary motion, connect by the parallel key between reduction gear no. 2 and the eccentric wheel, the eccentric wheel drives the screening sand frame through bearing and connecting rod and be horizontal migration on screening sand machine support frame, install the husky net of pore above the screening sand frame, the top of the husky net of pore is the gross porosity screen cloth. The utility model discloses simple structure, the preparation is convenient, and the replacement is sieved by hand, and the screening efficiency height is separated the people and is released from simple repetition and in heavily just working.