The invention relates to an early-disassembling formwork system and a construction method thereof. The formwork system comprises top formworks, side formworks, main ribs and bearing structures. Secondary ribs are arranged at the bottoms of the top formworks, the side formworks are erected on the side parts of the top formworks, each main rib is arranged between every two adjacent top formworks, the main ribs are connected with the secondary ribs in a supporting mode, the top faces of the main ribs are flush with the top faces of the top formworks, the bearing structures are arranged between the main ribs and connected with the main ribs in an inserted mode, the top faces of the bearing structures are flush with the top faces of the top formworks, and the bearing structures are supported on supporting faces. The top faces of the bearing structures are flush with the top faces of the top formworks, so that poured structures are made to be directly located on the tops of the bearing structures, only supporting structures of the bearing structures need to be reserved when a certain strength is reached, and the rest of the components can be directly disassembled; besides, in the disassembling process, adjusting operation is not needed, and the main ribs, the secondary ribs, the side formworks and the top formworks can be directly disassembled.