The invention discloses an antique building reinforced waterproof roof and a construction method thereof. The reinforced waterproof roof comprises a roof area and a cornice head area. The roof area comprises a wooden rafter, a sheathing brick layer, a wooden keel, a treated wood base layer, a first waterproof roll layer, a second waterproof roll layer, a convex plastic drainage board layer, a non-woven fabric layer, a steel mesh layer, a cement mortar mortar bed and a tile-roofing layer sequentially from inside to outside. The cornice head area comprises a wooden rafter, a hood-rafter-to-rafter wood strip, a sheathing brick layer, a wooden fly rafter, an eave wood strip, a second sheathing brick layer, a roof boarding layer, a treated wood base layer, a wooden verge board, a stainless steel draining board, a first waterproof roll layer, a second waterproof roll layer, a stainless steel angle baffle, a convex plastic drainage board layer, a non-woven fabric layer, a cornice treated wood head and the like sequentially from inside to outside. Breakthrough and innovation are made on the basis of the conventional roof waterproofing process of antique buildings, timely drainage of water seepage is realized with the aid of a drainage and moisture permeable overhead channel set up, and safety coefficient of roof waterproofing of the antique buildings is improved substantively.