The invention relates to the technical field of environmental aerosol measuring, in particular to a simulated lung breathing device. The device comprises a sealing box, a lung model, an air collectingbag and an air pump, and the lung model and the air collecting bag are both arranged in the sealing box and are kept independent of each other; the lung model is connected with a lung pipeline leading to the outside of the sealing box; the air pump is connected with a suction pipeline, the suction pipeline is provided with a first valve and a second valve, and the first valve, the second valve and the air pump form a series loop; the air collecting bag is communicated with the suction pipeline and is communicated between the first valve and the second valve; the first valve and the second valve are three-way valves, and a valve port of each valve is kept to be communicated with air outside the sealing box; the air pump exhausts air from the air collecting bag, the air collecting bag contracts, the air pressure in the sealing box is reduced, airflow enters the lung model from the lung pipeline, and the inspiration process is completed; the air pump inflates the air collecting bag, theair collecting bag expands, the air pressure in the sealing box is increased, airflow flows out of the lung model along the lung pipeline, and the expiration process is completed.