Underground safety blowout prevention pressure control circulation switch

The utility model discloses an underground safety blowout prevention pressure control circulation switch which comprises a cylindrical upper connector, a cylindrical adapter connector, a cylindrical connecting connector, a cylindrical main body and a cylindrical lower connector which are sequentially connected in a threaded mode. A cylindrical upper core shaft, an upper valve seat, an upper baffle, a shaft sleeve and a shear pin are embedded in the upper connector. Only the upper baffle of the safe blowout prevention pressure control circulation switch needs to be closed, a soluble ball is put into a tubular column, a shear pin on the side wall of the upper core shaft of the safe blowout prevention pressure control circulation switch valve is hit off through positive pressing, the upper core shaft is made to fall off, and at the moment, the baffle of the safe blowout prevention pressure control circulation switch valve is in a closed state under the action of a torsional spring; and blowout prevention of an i