An ornamental plate structure includes a supporting base and a sliding button. The sliding button includes a button portion, a first sliding portion, and a fastening portion whereon an incline and a wedging slot are formed. The ornamental plate structure further includes an ornamental plate having a plate, a hooking component and a fixing component. The fixing component includes a wedging portion, a second sliding portion and an assembly surface. The wedging portion wedges inside the wedging slot after the assembly surface slides relative to the incline at a predetermined distance so as to fix the ornamental plate on the supporting base. The button portion is pushed to slide the first sliding portion relative to the second sliding portion so as to separate the wedging portion from the wedging slot. The ornamental plate structure further includes a resilient component for driving the sliding button.