The utility model relates to an oil and natural gas bores completion technology field, in particular to well head annular space sealing device. About the device's the urceolus on the outer wall of both ends all processing have the external screw thread, the urceolus suit is in the inner tube outside, threaded connection compresses tightly the nut on the inner wall of urceolus upper end, compress tightly the nut up end on processing fluted, compress tightly the nut lower extreme and support on the upper seal ring, upper seal ring, a plurality of separate unit, lower seal ring from last to installing in order down between urceolus and inner tube in the annular space, all through sealing up between installation sealing washer and inner tube, the urceolus on the inside and outside wall of upper seal ring sum lower seal ring. The utility model discloses a can effectively seal annular space between production casing and intermediate casing, scurry on blocking the natural gas, easy operation, safe and reliable, the operating expenses is low to reduce the risk of well head annular space area pressure and issue handling.