The invention discloses a lung function recovery training device which comprises a piston cylinder, a piston, a piston rod and a self-adjusting resistance-increasing mechanism, the piston is in sliding sealing fit in the piston cylinder, the piston rod is fixedly connected to the second end of the piston, the self-adjusting resistance-increasing mechanism is fixedly installed on the outer wall of the piston cylinder, and the self-adjusting resistance-increasing mechanism is fixedly connected to the second end of the piston. The self-adjusting resistance-increasing mechanism is arranged in parallel with the piston cylinder, two or more air outlet holes are distributed in the cylinder wall of the piston cylinder in the axial direction of the piston cylinder, and the air outlet holes are in fluid communication with resistance-increasing assemblies, with different resistances, of the self-adjusting resistance-increasing mechanism through pipelines. By arranging a piston, a piston barrel and a spring, the lowest resistance can be provided for a user, the training requirement of a patient with poor respiratory capacity is met, by arranging a first-stage resistance increasing barrel, gas is introduced into a resistance increasing airbag on a first movable plate to expand, so that the resistance increasing airbag is attached to the inner wall of the first-stage resistance increasing barrel, and the advancing resistance of a piston rod is increased; the training intensity is automatically improved.