The traditional toilet caisson backfill material is generally made of construction waste or ceramsite, and its disadvantages are high cost, long time-consuming, uneven bulk density (there are dead angles), heavy foundation load, poor anti-leakage effect, poor seismic resistance, and laborious repair. Backfill treasure adopts a new foaming technology, a little foaming material and water in a short period of time to foam to 4-7 times the volume, and then uses the exclusive formula to stabilize the foam and enhance the waterproof treatment, the foamed concrete formed has the advantages of light weight, heat insulation, waterproof and seismic resistance, tensile resistance, high strength, and good filling compactness.