The weight percentage of a constructional foaming agent is that the anion surface active agent is 40-70%, the cationic surface active agent is 5-30%, the foam stabilizing agent by 5-15%, and the filling agent by 5-15%. The solid raw material is cracked into particle with the diameter smaller than 100 meshes, and mixed evenly, then liquid raw material spray is agglomerated on the solid raw materialwhich is mixed evenly, stirred evenly and dried, even powder is conformed. The invention has advantages of simple process, and being easy to be shaped, hard to be degenerated and convenient for transportation, which has good water solubility and high stability, with less reduction of concrete strength, low cost etc.