The utility model discloses a heat insulating roof made of construction waste and belongs to the field of building materials. The heat insulating roof comprises a roof and a plurality of precast blocks prepared by blending foamed concrete in the construction waste serving as an aggregate; the precast blocks are made to have the thickness of 10-20cm and are uniformly arranged on the outer layer of the roof; cement grout is poured between the precast blocks; an impermeable layer is arranged on the precast blocks and the cement grout. The heat insulating roof is directly arranged on the outer layer of a roof top or the outer layer of a building roof, the precast blocks are arranged at intervals according to a design, the cement grout is poured between the precast blocks to seal seams, and after maintenance is finished, the impermeable layer is arranged on the roof layer. The heat insulating roof is low in density, the load of the building roof can be reduced, and the bearing capacity of a building is improved; the construction waste in cities is treated, land occupation is reduced, environmental pollution is reduced, the construction waste is recycled, and great social and economic benefits are achieved.