A device for assembling a heat dissipation fan in a computer includes a cage, a handle, and a movable portion. The handle is rotateably fixed on the cage, the handle has a pushing pole and holes are defined at each distal end. The movable portion is movably and elastically connected to the cage. The movable portion includes a plate with a first limit pillar and a second limit pillar spaced from the first limit pillar; and an elastic element abutting the first limit pillar.