A computer mouse with adjustable decorative wing includes a main housing, a bottom board covered on the bottom surface of the main housing, a decorative wing disposed on one side of the main housing and a distance-adjusting mechanism. The decorative wing has a fastening end fixed to the main housing, and a movable end. There is a adjustable distance between the movable end and the main housing. The distance-adjusting mechanism is disposed on the main housing and contacts the movable end of the decorative wings for adjusting the distance of the movable end and the main housing of the decorative wings. A width of the computer mouse therefore is changed. The decorative wings on two sides of the computer mouse of the present invention can be expanded to support fingers for suiting to different users' palms.