In order to better understand the impact of diffusion dike flood on the local economy in midstream of Qinhe Rever,the paper used GIS software to process basic data from Duanshi estuary to Runcheng in the middle reaches of Qin River and used interpolation method to generate the topographical map of flood areas. The model of loss rate was used to assess the loss status of flood area. When the river meet the flood of one time per 100years, the overtopping dike incident can occur and cause the direct economic loss to 90.1758million yuan and indirect economic loss to 16.23million yuan. The calculation and analysis of dike flood loss in the midstream of Qinhe River will provide rational basis for policy makers and river supervisors to do staff scheduling so as to avoid disaster.