The invention relates to a construction method for a water-seal curtain being crosswise sleeved on a biaxial
soil cement agitator. The construction method comprises the following steps: first step, a field is leveled; second step, a biaxial
soil cement agitator is positioned; third step, agitation is performed for the first time and an
agitator head is descended to the depth of a
pile; fourth step, agitation is performed for the second time and the agitator head is ascended to the top of the
pile; fifth step, agitation is performed for the third time and the agitator head is descended, and the third step is repeated; sixth step, agitation is performed for the fourth time and the agitator head is ascended, and the fourth step is repeated to form a first columnar induration; seventh step, a
mortar feeding tube is cleaned; eighth step, the agitator is advanced for two
pile positions; ninth step, the third, the fourth, the fifth and the sixth steps are repeated to form a second columnar induration; tenth step, the seventh step is repeated; eleventh step, the
mortar is dropped back for a pile position, then the third and the fourth steps are repeated, crosswise sleeve joint is performed to the two columnar indurations, and a branching between the two columnar indurations is eliminated; twelfth step, the seventh step is repeated; thirteenth step, the agitator is advanced for three pile positions, then the fourth, the fifth and the sixth steps are repeated, and the construction of a fourth columnar induration is carried out; fourteenth step, the tenth, the eleventh, the twelfth and the thirteenth steps are repeated in sequence, and non-branching water-seal curtain is continually accomplished. The method greatly enhances the integrity and the barrier property of the water-seal curtain, saves space, and saves the construction cost.