The present invention provides a pixel driving circuit and a display panel. The pixel driving circuit includes a light emitting module and a compensation driving module which are electrically connected. The compensation driving module includes a doubled-gate driving thin film transistor, and is configured to charge a bottom gate of the doubled-gate driving thin film transistor and adjust a threshold voltage to an initial value in an initial stage. The compensation driving module receives a reference voltage to discharge the bottom gate of the doubled-gate driving thin film transistor in a threshold voltage compensation, realizing a compensation of the threshold voltage.