Drilling tool special for sampling of sand soil layer

The utility model discloses a special drilling tool for sampling a sand soil layer. The special drilling tool comprises a movable seat, the portal frame is fixedly connected to the top of the moving seat; the sampling mechanism comprises a positive and negative rotation motor capable of being fixedly connected to the top of the portal frame, an output shaft of the positive and negative rotation motor is fixedly connected with a threaded shaft, the threaded shaft is in threaded connection with a threaded sleeve, the side face of the threaded sleeve is fixedly connected with a driving seat, and the bottom of the driving seat is fixedly connected with a drill rod; a sampling assembly is installed at the bottom of the drill rod and comprises a sampling drill bit, the top of the sampling drill bit is fixedly connected with a threaded seat, the threaded seat is in threaded connection with a threaded head, the top of the threaded head is fixedly connected with the bottom of the drill rod, and a sampling assembly use