The invention discloses a cam type sampling device for polluted soil. The cam type sampling device comprises a drill bit, wherein the drill bit is fixed at the bottom of a drilling rod; spiral bladesare arranged on the outer wall of the drill rod; a sampling rod is fixed at the top of the drilling rod; rotating holding rods are arranged on two sides of the top of the sampling rod; an adjusting ring is arranged at the top of the sampling rod; another rotating holding rod is arranged at the bottom of the adjusting ring; the rotating holding rod is arranged inside a rotating hole in a penetration manner; a sampling tank is arranged at the bottom of the sampling rod; the bottom end of the rotating rod is fixed at the left end of the connecting rod; a driving rod is fixed at the bottom of theright end of the connecting rod; a sampling cylinder is fixed by the driving rod and a support rod; a collection cavity is formed inside the sampling cylinder; a sampling shovel is arranged on the wall of the sampling cylinder; a shovel hole is formed in the bottom of the sampling shovel; a cylinder cover is in threaded fixation on the left side of the bottom of the sampling cylinder; and a sampling opening is formed in a side wall in a horizontal position of the sampling cylinder, of the sampling tank. By adopting the cam type sampling device, soil can be sampled and collected by using a camtype rotating sampling cylinder.