Underground blowout preventer

The utility model discloses an underground blowout preventer, which comprises a central pipe, the inner framework is a rigid body; a space is reserved below the end, away from the lower inner framework, of the pushing body in the axial direction of the center pipe, and the pushing body is fixedly connected with the center pipe through a pin in the original state; the rubber ring is arranged on the outer side of the inner framework in a sleeving manner; in the original state, the inner framework extends in the axial direction of the central pipe and does not support the rubber ring outwards. The blowout preventer is high in supporting and sealing reliability. 本实用新型公开了一种井下防喷器，包括：中心管；内骨架，内骨架为刚性体；推动体，推动体远离下内骨架的一端的沿中心管轴向方向的下方留有空间，原始状态时推动体通过销钉固定连接中心管；橡胶圈，其套设在内骨架外侧；原始状态是：内骨架沿中心管轴向方向延伸设置且并未向外撑起橡胶圈。该防喷器支撑封闭的可靠性高。