A pixel driving circuit includes a first thin film transistor having a double-gate structure, a conductive layer and a second thin film transistor. The first thin film transistor includes a first active layer. The first active layer includes a first and second semiconductor portions and a conductor portion located therebetween. The conductor portion has a first doping concentration. The conductive layer is at least partially opposite to the conductor portion, so that the conductive layer and the conductor portion form a capacitor. The conductive layer is configured to electrically connect to an initial voltage terminal. The second thin film transistor includes a second active layer and a first gate. A portion of the second active layer directly opposite to the first gate has a second doping concentration, and the second doping concentration is lower than the first doping concentration.