1. A method for recognizing and tracing a gesture to provide an image sensor ( 10 ) to fetch a gesture image, the method comprising the steps of: (a) pre-processing the gesture image; (b) detecting a largest moved block of the gesture image and defining the largest moved block as a gesture block; (c) analyzing a feature of the gesture block to determine the gesture block is a moved verification gesture or a command gesture; (d) determining whether the gesture block is successively changed to a moved gesture when the gesture block is the moved verification gesture; (e) detecting and tracing a center coordinate of the moved gesture when the gesture block successively changes to the moved gesture, and the moved gesture does not stop moving with duration over an action time; and (f) outputting the center coordinate of the moved gesture and re-performing the step (a).