The invention relates to a soil sampling device for measuring the bulk density of soil. The invention adopts a mechanical soil sampling device which is provided with a machine frame, wherein one end of the machine frame is provided with a longitudinal cutting mechanism, the middle part of the machine frame is provided with a soil sampler bracket, the bracket is provided with a soil sampler, and the other end of the machine frame is provided with a transverse feeding mechanism. The soil sampler is composed of a soil sampling pipe, a ring-shaped cutter, a soil sampling pipe shoe and a cutter-pushing ring, wherein the interior of the soil sampling pipe is provided with a plurality of ring-shaped cutters, one end of the ring-shaped cutter in the soil sampling pipe is provided with the cutter-pushing ring, a gap is arranged between the soil sampling pipe and the ring-shaped cutter, one end of the soil sampling pipe is provided with a convex ring matched with the soil sampler bracket, the other end of the soil sampling pipe is provided with the soil sampling pipe shoe, the soil sampling pipe shoe is connected with the screw thread of the outer wall of the soil sampling pipe, and the outer wall of the soil sampling pipe is provided with a scale. The invention has the advantages of the simple structure, the convenient use, the reliable operation, gaining a plurality of layers of soil sample once, the high efficiency, and ensuring the sampling quality.