By analyzing issues of flood, population, economy, ecology etc. that the wetland of Dongting Lake confronted before, the article comes to the conclusion that the chief task of the wetland in this region is to meet the need of flood control in the middle reaches of the Yangtze River. The computing result of flood model proves the great function of the wetland for flood regulating. However, it is the population that restricts the realization of the function, and thereby causes a series of problems. Therefore, through analyzing the historical and objective economic society development, the article puts forward the "Human-Flood-Ecology" to establishing the theoretical developing mode of "Safe Habitation-Risk Producing" on the wetland area; thereby, achieving the intention of harmonious relations between human and nature, and providing reference to the relevant macro decision-making of the nation.