A wheel cover unit for front wheels of trucks or buses includes a wheel cover, two attaching members and a cover. The wheel cover is provided with an outer convex platform having a central hole, and the periphery of the central hole is annularly provided with a plurality of nut convex covers and a plurality of through holes. The inner edge of the central hole is vertically and backwardly provided with a hole ring having corresponding two pairs of slots, wherein each slot extends to the central hole with a lock tab. Each attaching member is provided with a connecting portion and two connecting pieces. The connecting portion is locked with the bolt of the wheel and the connecting piece is locked with the lock tab via a screwed element, so as to assemble the wheel cover to the front wheel of the truck or bus.