A special horizontal cutting and drilling integrated clamp for a gravity hub comprises a clamping portion, a rotary portion and a rotary locking portion. The clamping portion is provided with a chuck rotary shaft (10), the rotary portion is provided with a chuck rotary chain wheel (2), the rotary locking portion is provided with a locking quick wheel (4), the clamping portion and the rotary portion are connected through the chuck rotary shaft (10) and the chuck rotary chain wheel (2), and the clamping portion, the rotary portion and the rotary locking portion are connected due to the fact that the locking quick wheel (4) is fixed to the chuck rotary shaft (10). The clamp is characterized in that the clamping portion clamps the hub, the rotary portion rotates by 360 degrees, a machine tool cutter cuts a hub dead head, the rotary portion stops, the rotary locking portion carries out locking, and a machine tool drills the hub. By means of the structure, the clamp meets the machining requirements of cutting the dead head and drilling a center process hole after one-time clamp, saves operation time, reduces the manufacturing cycle of the hub, and saves manufacturing cost.