The invention discloses a preparation method for special mortar for utilizing wastes to prepare a wall material. The method comprises the following steps: firstly, respectively weighting raw materials by weight part; crushing the solid wastes of the construction, adding pentaerythritol, barium stearate, shell powder and lime stone, keeping temperature and stirring, thereby acquiring a mixture A; mixing slag powder, attapulgite and portland cement, adding water and stirring, and adding sodium triphosphate and ethyl naphthol, thereby acquiring a mixture B; uniformly mixing graphite powder, magnesium sulfate, polytetrafluoroethylene fibers, calcium phosphate, aluminum dihydrogen phosphate and tri-octanoic-butyltin, thereby acquiring a mixture C; mixing, pouring or spraying the mixture A, the mixture B, the mixture C and simethicone into a mould, thereby acquiring the special mortar. The special mortar has the advantages of low material loss and waste, high adhesive strength, low dry shrinkage, excellent anti-freeze durability, low thermal conductivity, high heat retaining property, excellent peaceability, environmental protection, non-toxic property, full utilization for industrial wastes and construction rubbish and development of circulating economy.