The Huang-Huai-Hai Plain of about 0.3 million km²,is one of the lar-gest plains in China.It has been an important agricultural area.Its natural conditions are generally favorable for agriculture,but there are some serious disasters,such as drought,waterlogging and salinization.For this reason, the output of farm produce is lower and more unstable for a long-term. The analysis of reason causing all disasters mentioned-above reveals that the principal contradiction is the disequilibrium of supply and demand of water,especially the damage caused by flood from breaches of the Huanghe River.The formation of the Huang-Huai-Hai Plain resulted from the Huan-ghe River itself.For this end,the quantity of silt in the Huanghe River must be decreased first of all.That means that the amount of silt coming from the Loess Plateau must be controlled.The only way is to take some important measures of water and soil conservation,among which,the biolo-gical step is most essential.