Abstract: The characters of miro-hydrological cycle in waterlogged lowland has systematicly explained in this paper.By using optimal identification method to solve the inverse problems of groundwater,the recharge quantity of soil water through capillary rising from groundwater was obtained.The application conditions and the advantages and disvantages of the soilwater flux method were reviewed.Then the quantity of irrigation and recharge quantity of soil water by precipitation was successfully obtained by using this method.Finally,the water use efficiency of crops in the waterlogged lowland was calculated.