Provided are a pixel driving circuit, a driving method thereof, a display panel and a display device. The pixel driving circuit includes a pulse-width adjustment module, an amplitude adjustment module and a light-emitting element. The pulse-width adjustment module is electrically connected to a sweep signal terminal and includes a pulse-width drive transistor. The pulse-width drive transistor is configured to supply a sweep signal supplied from the sweep signal terminal to the amplitude adjustment module. The amplitude adjustment module is configured to control the light emission duration of the light-emitting element according to the sweep signal. In the provided pixel driving circuit, driving method thereof, display panel and display device, a switching-off voltage for switching off the amplitude adjustment module does not need to be supplied additionally, thereby reducing the circuit complexity of a pixel driving circuit.