In the process of preventing flood there are three serious mistakes, .e.，"neglecting South but saving North","storing flood and reclaiming"， and"abandonning the upper but protecting the lower",of which constructing Three-Gorge Dam having been brewed would make greater mistake than the former two because of the uncorrect guidline of"abandonning the upper' but protecting the lower".The measures to harness Yangtze River should be practiced in order and in comprehensive planinng, including to。? :elerating the flood-prevention engineers on plain seriously, to eliminatr the retards in channel, to establish law strictly and to implement it，to dispel hidden danger in order to prevent the bursting of JinJiang embankment reso- lutly, to give up land planted for lake in order to recover "village rich in fish and rice"，to harness Duntinhu Lake actively,to build reserviors on branch rivers in combination with multiple use,to strengthen soil conservation in practice and to raise the level of science and management.