The invention relates to a waterproof material, particularly a novel wide-coverage waterproof coiled material substitutable for polyurea waterproof paint and a preparation method thereof. The invention solves the problems of high construction and formularization cost and the like in the existing spray-coating polyurea waterproof paint. The wide-coverage waterproof coiled material substitutable for polyurea waterproof paint is prepared from chlorinated polyethylene, a filling reinforcer, a softening plasticizer, phenolic antioxidant, a thermal stabilizer, a light stabilizer and a lubricant. The preparation method comprises the following steps: mixing the raw materials, and stirring; granulating by sequentially treating the mixture with a plastic mixing mill, a compounding mill and a dicing machine; putting the granules into a single screw extruder, and forming in a die; and rolling by a tri-roller cooling calender to obtain the waterproof coiled material. The novel wide-coverage waterproof coiled material substitutable for polyurea waterproof paint has high softness, high percentage of elongation and high rebound elasticity in the rubber-type waterproof coiled material on the premise of maintaining high tensile strength in the plastic-type waterproof coiled material, and thus, exceeds the construction standard for spray-coating polyurea waterproof paint; and the novel wide-coverage waterproof coiled material substitutable for polyurea waterproof paint has the advantage of low production cost and has wide application prospects.