The invention provides a foam concrete heat preservation layer construction method and foam concrete slurry pumping equipment. The foam concrete heat preservation layer construction method comprises the following steps that (1), a foaming agent is foamed, foamed foam and cement slurry are stirred uniformly, and foam concrete slurry is prepared; (2), the foam concrete slurry is pumped to a flat roof or a slope roof to be cast in place, and the pumping mode is that the foam concrete slurry pumping equipment is placed on a lower structural layer of the roof, and slurry pumping pipes of the foam concrete slurry pumping equipment adopts multiple sets of detachable slurry pipes; and (3) curing is conducted after trowelling. The foam concrete slurry pumping equipment used in the foam concrete heat preservation layer construction method comprises a rack, a foaming system, a stirring system and a pumping system, wherein the foaming system, the stirring system and the pumping system are mounted on the rack. By constructing foam concrete on the roof, any vibration is not needed in the construction process of the roof foam concrete, so that labor intensity is reduced, the construction cost is low, and environmental friendliness and economy are achieved.