The invention relates to a soil sampling device, and in particular to a mechanical soil sampling device. The mechanical soil sampling device comprises a complete machine rack, an adjusting mechanism,a sampling mechanism, foundation bolts, mounting nuts, lifting mechanisms I and lifting mechanisms II; a spiral body can be made to automatically rotate while moving downwards through power output bya motor, and the spiral body collects and samples soil; the position of the spiral body in the space can be adjusted by rotating an adjusting handle and a sampling handle, and therefore the spiral body can collect soil at any position in a designated area; and the device can be fixed by the foundation bolts and the mounting nuts to bring convenience to collection, the height of the device can be adjusted by rotating the lifting mechanisms I to meet more using requirements, the foundation bolts and the mounting nuts can be made to be not fixed to the ground any more by rotating the lifting mechanisms II, the two lifting mechanisms II push four moving wheels to make contact with the ground, and then the device can move.