The invention provides a drift diameter gauge assembly and a drafting device. The drift diameter gauge assembly comprises a drift diameter gauge and a driving device; the drift diameter gauge comprises a connecting rod and a drift diameter head, and one end of the connecting rod is fixedly connected with the top end of the drift diameter head; the drift diameter head is provided with a tool bit; and the driving device is fixedly connected with the other end of the connecting rod and used for driving the drift diameter head to rotate. According to the drift diameter gauge assembly and the drafting device, the driving device drives the drift diameter head to rotate, the tool bit on the drift diameter head can rotationally clear obstructions such as deposited wax, oil dirt and water scale onthe pipe wall, it is ensured that drafting operation is smooth, the situation that the drift diameter gauge is blocked and jammed in a well, and consequently the drafting operation is affected is effectively avoided, and the drafting efficiency is improved.