A pixel array substrate including a substrate having at least one via, at least one conductor disposed in the at least one via, pixel units, scan lines electrically connected to the pixel units, at least one shift register and at least one bus line is provided. The pixel units, the scan lines and the at least one shift register are disposed on a first surface of the substrate. The at least one shift register is used to transmit a first gate signal to the corresponding scan lines. The at least one bus line is disposed on a second surface of the substrate. The at least one bus line is electrically connected to the at least one shift register by the at least one conductor.