Aim to improve upper limb rehabilitation effect, we design and develop an Image-projective Desktop Arm Trainer (IDAT). Compared with conventional therapy, IDAT provides a more effective and interesting training method. IDAT's goal is to maintain and improve patients' upper limb function by training their eye-hand coordination. We select step-on interface (SOI) as the input system which makes trainees can operate IDAT with hand directly. Trainees can make a customized training setting. It can provide motivation and accomplishment to trainees and maintain their enthusiasm and interest. So IDAT provides a much different human robot interaction with pervious upper limb rehabilitation robots that equip a joystick or controller to operate remotely. We propose this idea in 2007 and have applied SOI on some mobile robots. Now we apply it on IDAT to make a new way to upper limb rehabilitation.