A mounting device includes a clamping device, a spacing device, and a receiving device. The clamping device includes an upper clamping element and a lower clamping element. The upper clamping element includes a first side plate and an upper clamping plate, the first side plate defines a guiding element and a number of position holes thereon thereon. The lower clamping element includes a second side plate received in the guiding element and a lower clamping plate opposite to the upper clamping plate. The second side plate defines a spacing hole therethrough. The spacing device is positioned on the first side plate and extends outward a position pole, the poison pole penetrates the position hole and receives in the spacing hole for fixing the lower clamping element. The receiving device is rotatably connected with the first side plate and defines a receiving room.