A device for bone fixation comprises an expansion part and a covering part. The expansion part has a fixing end and a top end and provides an expansion structure for being adjustable between a state of expansion and contraction. The covering part has a front end and a joining end, wherein the front end thereof is joined to the top end of the expansion part, and the joining end thereof is attached to the fixing end of the expansion part. The covering part is employed to cover the expansion structure. After the expansion part and the covering part are added to the bone, the covering part is unfurled to spread to the expansion state, and the medical filler is injected or pushed into the covering part.
