The invention relates to a pixel driving circuit, a display panel and a driving method thereof, and relates to the technical field of display, wherein the problem in the prior art that a driving thinfilm transistor (TFT) works over a long period of time and then the threshold voltage of the driving TFT can generate a certain drift so as to cause the brightness displayed by an AMOLED display screen is not stable enough can be solved. The pixel driving circuit comprises a light-emitting unit, a driving unit, a switch unit and a storage capacitor unit. The driving unit comprises a first sub-driving unit and a second sub-driving unit. A circuit change-over unit comprises a first switch change-over unit and a second switch change-over unit. The two ends of the first switch change-over unit areelectrically connected with the first end of the light-emitting unit and the first sub-driving unit respectively. The two ends of the second switch change-over unit are electrically connected with the light-emitting unit and the second sub-driving unit respectively. The circuit change-over unit is used for switching the conducting states of the first switch change-over unit and the second switchchange-over unit. Compared with the prior art, the drift caused by the threshold voltage of each driving unit can be reduced. The brightness stability of the light-emitting unit can be improved.