A portable electronic device and a touch operation method thereof are provided. When the portable electronic device is at an image capturing mode, a touch event on a touch screen is detected. Next, a shooting countdown time is determined according to a location of an end point of the touch event on a predetermined path. When no touch event is detected on the touch screen, executing the counting of the shooting countdown time, and an image capturing unit is triggered to capture an image when the counting of the shooting countdown time is up. The user directly enables a timed shooting function and sets a shooting countdown time at the same time by dragging a shutter button, which provides the convenience while operation.