A pixel driving circuit for a light-emission-device-based display panel is provided, including a driving transistor coupled to a light-emission device per subpixel; a digital-driving circuit having a first input terminal configured to receive a pixel voltage signal corresponding to a grayscale level of a subpixel image to be displayed and a first output terminal coupled to a gate terminal of the driving transistor. The digital-driving circuit is configured to convert the pixel voltage signal to a digital signal and transform the digital signal to a pulse-width-modulation (PWM) signal outputted via the first output terminal to the gate terminal of the driving transistor. The PWM signal comprises a pulse width proportional to the grayscale level as a duty cycle in a period of driving the light-emitting device to display subpixel image.