Natural gas wellhead sealing cut-off device

The utility model provides a sealing and cutting device for a natural gas well mouth. The sealing and cutting device comprises a shell, a valve body, a valve core column, an action frame, an anti-rotation plate, a motor and a speed reducer, wherein an inlet flange, an outlet flange and an external interface are arranged on the shell; a valve cylinder and an inner connector are arranged at the twoends of the valve body respectively, the valve cylinder is fixed in the shell, a side valve hole in the valve cylinder is communicated with the inlet flange, and a port of the valve cylinder is communicated with the outlet flange. The valve core column is assembled in the valve barrel in a sliding and sealing mode and can plug the side valve hole, and a screw rod is arranged at one end of the valve core column and extends out of an inner connector of the valve body; the action frame is connected to an inner connector of the valve body, a driven bevel gear and a driving bevel gear which are meshed with each other are r