Temporary plugging tool for wellhead of oil and gas well

The invention discloses a temporary plugging tool for an oil-gas well mouth, and belongs to the field of oil-gas well development. Comprising a mandrel, a sealing piston and a screw, the mandrel is sleeved with an elastic sealing piece, the contact face of the mandrel and the elastic sealing piece is a conical face, and the elastic sealing piece is arranged on the front side of a station of the sealing piston; the mandrel is further sleeved with a fixing sleeve, the rear portion of the fixing sleeve is fixed to the mandrel, the sealing piston is sleeved with the front portion of the fixing sleeve, and a channel for movement of the sealing piston is formed between the mandrel and the fixing sleeve. A cavity I is formed in the mandrel, the cavity I is communicated with the channel through an open hole, and a cavity II communicated with the cavity I is formed in the screw rod. The hydraulic expansion technology is adopted, the sealing piston drives the elastic sealing piece to move forwards and deform after movi