Air collecting bag for expiration test

The utility model discloses an air collection bag for an expiration test. The air collection bag comprises a bag body, one side of the bag body is fixedly connected with a connecting pipe; flow guide assemblies are arranged on the inner sides of the connecting pipes; the flow guide assembly comprises a guide pipe, one side of the guide pipe is fixedly connected with a ball, the circumferential face of the ball is provided with a one-way hole, the other side of the guide pipe is connected with a connecting pipe in a penetrating mode, the circumferential face of the guide pipe is provided with an air inlet hole, and a movable plug is movably arranged on the inner side of the connecting pipe and arranged on the guide pipe in a sleeved mode. The air supply pipe jacks up the movable plug in the pipe body to move inwards, so that the air inlet hole formed in the peripheral surface of the guide pipe sleeved with the movable plug is communicated with the air supply pipe, air in the bag body is more convenient to coll