This paper reckons there was an alteration during mid-late Qing Dynasty,at which time the problem of population and environment becomes serious,promoting a conspicuous progress in radical treatment of river,methods to solute water-sediment problem.During this time,people recognized the relation of flood,mountain reclamation and population increase,took seriously in the upstream to prevent and control soil erosion.They recognized the relation of flood,marsh reclamation and population increase,reached an agreement of abandoning reclamation to let with the water.Meanwhile,people thought more of restoring river’s natural state and building a whole picture in river controlling.Regretfully,this trend did not lead to universal practices in late Qing and early time of Republic of China,partly because of the inherent disadvantage of China’s traditional science and technology,its "practical model",which prevents possible approaches just for their long time taking;partly it’s because of the lack of supporting science and technology.
