A vibration damping mechanism includes a frame, cushioning members, a heat sink, and fastening members. The frame has a base plate and supporting arms disposed on the base plate. Each cushioning member is disposed on a respective one of the supporting arms, and has a through hole. The heat sink supports a hard disk thereon such that the hard disk lies flat against and is secured on the heat sink, and has a plurality of fastening holes. Each fastening member extends through the respective through hole and threadedly engages the respective fastening hole such that the heat sink is suspended on the supporting arms and abuts against the cushioning members. Thus, the area of contact between the heat sink and the hard disk is increased to enhance the heat transfer efficiency, and the cushioning members provide the heat sink and the hard disk with a cushioning effect.