An automatic rod connecting and detaching mechanism for a grain sampler relates to the field of agricultural equipment and comprises a stand column, a sliding rail is fixed on the side surface of thestand column, two groups of sliding seats are mounted on the sliding rail, and the automatic rod connecting and detaching mechanism further comprises a connecting rod, the drill bit is fixed on one ofthe sliding seats on the sliding rail; the clamping mechanism is fixed to the other sliding seat on the sliding rail, and the drill bit is located on the upper portion of the clamping mechanism; therotary table mechanism is fixedly arranged on the stand column on the lower portion of the sliding rail, and a clamp is fixed to the upper portion of the rotary table mechanism; the drill bit, the clamping mechanism and the clamp are located on the same straight line, and the straight line is parallel to the axis of the stand column. The sampling device is simple in structure, the clamping mechanism, the drill bit and the rotary table mechanism are matched with one another to complete connection and disassembly of a plurality of sampling rods, it can be guaranteed that the sampling rods are connected or disassembled one by one in the whole process, orderly and rapid change-over can be achieved, and the working efficiency of the sampling device is improved.