Abstract: Without any hydrologic monitoring data, this paper calculate the water levels and discharges before and after releasing the flood water, in light of the flow data in high water period and the flood releasing flow data as well as river valley section parameter, and evaluate the disaster possibility led by flood releasing, by comparing the calculated results with the height of farmland and cottage along the riverbank. The result proves that the section bearing capacity is 491.091 m3/s and 476.219 m3/s on section A-A and C-C respectively, which is comparatively safe under the condition of releasing 412 m3/s in flow; but the section bearing capacity is 365.002 m3/s and 160.675 9 m3/s on section B-B and D-D, which will possibly lead to flood disaster under that situation.