Quick-mounting wellhead casing gas recovery device

The utility model discloses a fast-assembly wellhead casing gas recovery device which comprises a tee joint, a lower connector and a side connector of the tee joint are respectively connected into anoil pipe of a Christmas tree, and a tubular valve body is arranged in the tee joint. A fixing frame is arranged at the lower end of the valve body, a torsional spring is arranged on the inner side ofthe fixing frame, a sealing gasket is installed on the torsional spring, and the sealing gasket blocks the lower end of the valve body under the action of return pressure of the oil outlet pipeline and torsion of the torsional spring; the upper interface is provided with a tubular main body; wherein a cylindrical connecting body is embedded in an upper port of the main body, a valve core cover isexternally connected to a lower port of the connecting body, a compression spring is arranged in the valve core cover, a valve core is arranged in the compression spring, the valve core blocks the lower port of the connecting b