A connection device for a drum set has a connecting bridge, multiple resilient pads and a clamping device. The connecting bridge has a base board and two connecting arms. The connecting arms protrude respectively from two sides of the base board and each has a connecting end for connection to an adjusting rod attached to a drum shell of a drum. The resilient pads are mounted respectively on the connecting ends of the connecting arms and are mounted around the adjusting rods. The clamping device is securely mounted on the base board and has a clamping base, a clamping leaf, a locking rod and a locking element. Therefore, the connection device allows the drum to vibrate for improved timbre.