A gear self-tightening drill chuck, comprising a rear pressing cover, a rear body, a main body, a front sleeve, a plurality of clamping jaws, and driven bevel gears in a same number as the clamping jaws, wherein the rear body is arranged in the main body; a driving bevel gear is provided at one end of the rear body; a big end of the driving bevel gear is provided to be close to the rear body; a connection portion configured to be connected with an external device is provided at the other end of the rear body; the driving bevel gear is arranged in the main body, and is engaged with the driven bevel gears; the plurality of driven bevel gears are uniformly arranged around a center line which is an axis of the driving bevel gear; an inner hole of each of the driven bevel gears is provided with an internal thread; one end of each of the clamping jaws is provided with an external thread in cooperative use with the internal thread of the respective driven bevel gear; the main body is provided with clamping jaw holes capable of allowing the clamping jaws to pass therethrough and bevel gear holes configured to accommodate the driven bevel gears respectively; the main body has one end fixedly arranged in the front sleeve, and the other end provided with a rear hole rotationally connected with the rear body; the rear pressing cover is arranged at the other end of the main body, for fixing the rear body in the rear hole; the rear pressing cover, the rear body, the driving bevel gear, the main body, and the front sleeve are coaxially arranged; characterised in that each of the internal threads and each of the external threads are all multi-start threads, and wherein a lead angle α of each of the multi-start threads is in a range of 3.1° ≤ α ≤ 18.7°. wherein the rear body is arranged in the main body; a driving bevel gear is provided at one end of the rear body; a big end of the driving bevel gear is provided to be close to the rear body; a connection portion configured to be connected with an external device is provided at the other end of the rear body; the driving bevel gear is arranged in the main body, and is engaged with the driven bevel gears; the plurality of driven bevel gears are uniformly arranged around a center line which is an axis of the driving bevel gear; an inner hole of each of the driven bevel gears is provided with an internal thread; one end of each of the clamping jaws is provided with an external thread in cooperative use with the internal thread of the respective driven bevel gear; the main body is provided with clamping jaw holes capable of allowing the clamping jaws to pass therethrough and bevel gear holes configured to accommodate the driven bevel gears respectively; the main body has one end fixedly arranged in the front sleeve, and the other end provided with a rear hole rotationally connected with the rear body; the rear pressing cover is arranged at the other end of the main body, for fixing the rear body in the rear hole; the rear pressing cover, the rear body, the driving bevel gear, the main body, and the front sleeve are coaxially arranged; characterised in that each of the internal threads and each of the external threads are all multi-start threads, and wherein a lead angle α of each of the multi-start threads is in a range of 3.1° ≤ α ≤ 18.7°.