A rotary seat zero-clearance locking mechanism, comprising a locking mechanism mounted on a rotating disc in a seat rotation mechanism and at least one lockhole disposed on an outer circumference of a fixed disc in the seat rotation mechanism, wherein the locking mechanism comprises: a lock support fixed on the rotating disc; at least two lock pins (220, 230) horizontally and moveably configured in the lock support, wherein a first end (221, 231) of the lock pin (220, 230) is of a truncated-cone-shaped structure; and the first end (221, 231) of the lock pin (220, 230) is inserted into the lockhole, to implement zero-clearance locking by using wedging between the truncated-cone-shaped structure of the first end (221, 231) of the lock pin (220, 230) and the lockhole, a lock pin return spring (240, 250) sleeved on each lock pin (220, 230), wherein when the lock pin return spring (240, 250) is in a locked state, the first end (221, 231) of the lock pin (220, 230) is inserted, under the action of the lock pin return spring (240, 250), into the lockhole on the outer circumference of the fixed disc to lock the rotating disc, a release lever hinged to a top surface of the lock support through a release lever rotating shaft, wherein the release lever comprises a release end and an operation end, the release lever is driven by operating the operation end of the release lever to rotate, and the release end of the release lever drives the lock pin (220, 230) to move toward a release direction, so that the first end (221, 231) of the lock pin (220, 230) exits from the lockhole on the outer circumference of the fixed disc to release the rotating disc; and a release lever return spring connected to the release lever and the lock support or the rotating disc, wherein the release lever return spring drives the release lever to return to the locked state; and during releasing, the release lever return spring accumulates energy, characterized in that a silencing cap is sleeved on a tip of the first end (221, 231) of the lock pin (220, 230), and the silencing cap is in contact with the outer circumference of the fixed disc. a lock support fixed on the rotating disc; at least two lock pins (220, 230) horizontally and moveably configured in the lock support, wherein a first end (221, 231) of the lock pin (220, 230) is of a truncated-cone-shaped structure; and the first end (221, 231) of the lock pin (220, 230) is inserted into the lockhole, to implement zero-clearance locking by using wedging between the truncated-cone-shaped structure of the first end (221, 231) of the lock pin (220, 230) and the lockhole, a lock pin return spring (240, 250) sleeved on each lock pin (220, 230), wherein when the lock pin return spring (240, 250) is in a locked state, the first end (221, 231) of the lock pin (220, 230) is inserted, under the action of the lock pin return spring (240, 250), into the lockhole on the outer circumference of the fixed disc to lock the rotating disc, a release lever hinged to a top surface of the lock support through a release lever rotating shaft, wherein the release lever comprises a release end and an operation end, the release lever is driven by operating the operation end of the release lever to rotate, and the release end of the release lever drives the lock pin (220, 230) to move toward a release direction, so that the first end (221, 231) of the lock pin (220, 230) exits from the lockhole on the outer circumference of the fixed disc to release the rotating disc; and a release lever return spring connected to the release lever and the lock support or the rotating disc, wherein the release lever return spring drives the release lever to return to the locked state; and during releasing, the release lever return spring accumulates energy, characterized in that a silencing cap is sleeved on a tip of the first end (221, 231) of the lock pin (220, 230), and the silencing cap is in contact with the outer circumference of the fixed disc.