A touch device and a control method and a method for determining unlocking thereof are provided. The touch device includes image capturing units configured nearby a touch surface respectively, and light-reflected objects are configured around the touch surface. In this method, the image capturing units are used to detect a reflected signal to receive a first gesture on the touch surface when the touch device is operated in a touch-lock mode. The image capturing units emit a detecting signal along the touch plane and detect the reflected signal reflected from the detecting signal. It is determined whether the first gesture matches a first specific gesture. When the first gesture matches the first specific gesture, the touch device is operated in a touch-on mode. Touch information is provided when the touch device is operated in the touch-on mode but not provided when the touch device is operated in the touch-lock mode.