The present invention discloses a video adapter for installing video wall quickly. The video adapter includes a microcontroller unit; a number generating unit coupled to the microcontroller unit to set a number for one display in the video wall and transmit the number to the microcontroller unit; a first connector coupled to the display; and a second connector coupled to one end of a video and audio cable; wherein the microcontroller unit processes the number and transmits the number to a video and audio control device coupled to the other end of the video and audio cable; wherein the video and audio control device assigns corresponding video signals according to the number, so as to transmit the corresponding video signals to the display in the video wall.