The rotary kelly is located at the top of the drill tools. Its main function is to transmit torque and bear the weight of the drill tools when working. The rotary kelly is used to convert the rotation of the turntable into the rotation of the entire drill string and drill bit to break the formation, that is, to transmit torque and bear the full weight of the drill string. When drilling with turbodrills and screw drills, the rotary kelly bears the full weight and counter-torque of the drill string, and is also used to measure the well depth and provide a circulation channel.