The invention discloses an I-type impact air flow attenuator. The I-type impact air flow attenuator comprises an air flow buffering cavity, wherein an air inlet pipe and an air outlet pipe which are communicated with an inner cavity of the air flow buffering cavity are arranged at the two ends of the air flow buffering cavity; straight pipe sections of an emptying pipeline are communicated by the air inlet pipe and the air outlet pipe on the air flow buffering cavity; the air inlet pipe and the air outlet pipe on are arranged on a same straight line and are distributed in an I shape in the air flow buffering cavity. According to the I-type impact air flow attenuator, the properties of impact air flow and the emptying pipeline are considered comprehensively, basic principles of an interference type air flow buffer, a porous plate and a pore plate acoustic filter are integrated and extraction flow requirements of the emptying pipeline and the dynamic property of the impact air flow are considered comprehensively; the I-type impact air flow attenuator can be mounted on the straight pipe sections of the emptying pipeline outside a safety valve horizontally or vertically; the air flow buffering cavity is arranged, and the turning parts of the emptying pipeline are communicated by the air inlet pipe and the air outlet pipe on the air flow buffering cavity, so as to realize the effects of dissipating the energy of the impact air flow, reducing a coupling effect of the pipelines and guaranteeing the requirements of extraction flow.