The invention discloses a wellhead sealing device which is arranged on a wellhead and used for sealing the wellhead. The wellhead sealing device is characterized by comprising an adapter flange (4), an adapter connector (3), a hanging lifting sub (2) and a screw plug (1), wherein the adapter flange (4) is fixedly connected to the upper portion of a tubing head flange (9), the adapter connector (3) is fixedly connected to the upper portion of the adapter flange (4), the hanging lifting sub (2) is arranged in the adapter connector (3), the bottom of the hanging lifting sub (2) is connected with a sucker rod (6), the hanging lifting sub (2) can hang the sucker rod (6) when placed in a platform in the adapter connector (3), and the screw plug (1) is fixedly connected to the top end of the adapter connector (3) and can seal the adapter connector (3) to achieve wellhead sealing. By means of the wellhead sealing device, wellhead sealing is achieved, and oil and gas leakage is prevented; existing wellhole treatment requirements can be met, and leakage of oil and gas media in casing pipes can be eradicated.