A keyboard testing system includes a chassis; a retaining board; a plurality of guiding rods mounted between the chassis and the retaining board; a platform; a lifting device mounted on the chassis to drive the platform to move toward and away from the chassis; a motor mounted in the control box; a transmission device mounted in the control box; a key testing device movably mounted on the guiding rod. The motor drives the key testing device to move toward and away from the platform along the guiding rods by the transmission device.