A pixel driving system for AMOLED display device and driving method are disclosed. The pixel driving system for AMOLED display device includes a sub-pixel driving circuit and a node voltage generating module electrically connected to the sub-pixel driving circuit. Wherein the node voltage generating module is inputted with the a red-green-blue display data for processing the red-green-blue display data, obtaining an APL value of a current frame of the AMOLED display device, and according to the APL value and a preset node voltage calculation formula, the node voltage generating module generates a corresponding node voltage and outputting to the source of the driving thin-film transistor. Adjusting the gate-to-source voltage of the driving thin-film transistor by using the APL value, thereby adjusting the driving current flowing through the light-emitting diode to adjust the entire display brightness of the AMOLED display device.