A lens cap module is provided and positioned at a holding stand. The lens cap module includes a plurality of leaf pieces, a switch and a gear transmission. The leaf pieces are slidably positioned at the holding stand, and the leaf pieces can come into contact with or separated from one another. The switch is sliadbly positioned at the holding stand, and the gear transmission is positioned between the leaf pieces and the switch. The switch drives the leaf pieces to rotate through the gear transmission. Thus, it saves much more space for the leaf pieces and spends much less time closing or opening the leaf pieces.