The invention discloses a method for constructing kiloton-class water towers. The method includes steps of manufacturing water tower foundations; constructing concrete shafts; erecting concrete water tank formwork systems; mounting reinforcing steel bars of water tanks; mounting upper-layer formworks of the water tanks; manufacturing lifting load bearing steel frames; mounting the lifting load bearing steel frames; stripping the water tanks from forms; mounting lifting platforms and hanger rods; carrying out hydraulic lifting construction; arranging the water tanks in position; detaching the hanger rods, lead screw equipment and the lifting load bearing steel frames. The method has the advantages that computation configuration and experiments are carried out, accordingly, the purpose of lifting the kiloton-class water towers in-position can be achieved, the problem of zero rods or severe overload rods when existing hanger rods are lifted and changed can be solved, the safety can be guaranteed, and the method is the first choice for lifting extra heavy inverted cone water towers and water tanks which have huge volumes.