The present invention discloses a cambered waterproof insulating roof comprising two waterproof layers and two insulating layers with a cavity formed between the two insulating layers for soundproofing, wherein the roof is fixed to a steel structure; a copper sleeve is welded to the steel structure, and in threaded connection with a purlin hanger which is fixedly connected to a curtain wall plate through the roof; an upper cover is fixed to the upper portion of the purlin hanger, which comprises a loop in fixed connection with the purlin hanger; the loop is integrally formed with a crosswise downward covering surface with the edge of the covering surface formed into an inward V-shaped edgefold; the purlin hanger is surrounded with a vertical water retaining ring. According to the present invention, the insulation, waterproof and soundproof properties of the roof are guaranteed in such a mode of double insulation and double waterproofing with a cavity, and flexible waterproofing of an expansion allowance at the outside layer, the rigid covering surface and the vertical water retaining ring in the middle and the waterproof layers at the inside layer are provided in the position where the purlin hanger passes through, thereby guaranteeing that the waterproofness in the penetrating position of the roof is not lower than that of the roof and event superior to that of the overall roof.