Based on the statistics data from 1998 to 2007 in Guangxi Zhuang Autonomous Region,four factors:economic loss of flood,inst ability,contribution of economic loss to GDP,evaluation index of economic loss were used to assess the economic loss of flood disaster in this region.The results indicate that economic loss of flood is mainly affected by the hazard level.The proportion of the economic loss of agriculture maintains at 5%~15% of the total loss.The annual change of environmental instability in the region f luctuates obviously,but mainly with a declining trend year by year.The flooding economic loss is 0.5%~9.0% of GDP.The indexes of flooding loss can not only tell the annual change of the aroused factors of flood,the instability of the environment bearing disasters,but also accurately evaluate the flooding economic loss.At the same time,the indexes can be used as a method for instante valuation and preventions of the flooding loss and when flood takes place.According to the assessment results,the government is suggested to strengthen the defense capability of larger flood,increase investment in agricultural infrastructure and improve flood control standards of all prevention projects.