A mobile device protecting cover capable of storing a touch pen includes a touch pen slot and an insertion port disposed on the back side of the protecting cover. The touch pen slot has a press switch button disposed on an inner side wall for pressing the touch pen, and the inner side wall has a groove configured to be corresponsive to the press switch button, and extended from the insertion port as a starting end towards the other end of the touch pen slot. The protecting cover is used to cover a mobile phone or a tablet PC and insert the touch pen into the touch pen slot. When the touch pen is inserted or removed, the structure of the groove and the inner side wall achieves main effect of turning on or off the power by the touch pen.