A driving method and a driving device for a display panel, and a display device are provided. Each pixel of the display panel includes at least two primary-color sub-pixels of different colors and one mixed-color sub-pixel, and the driving method comprises: determining display power consumption according to the obtained brightness value of each of the primary-color sub-pixels; compensating for the brightness value of each of the primary-color sub-pixels according to the display power consumption; determining an output brightness value of each of the sub-pixels according to the compensated brightness value of each of the primary-color sub-pixels and a color coordinate of each of the sub-pixels; and outputting the output brightness value of each of the sub-pixels to a source driving circuit.