Abstract: This paper simply analysed the inundated area due to Hangzhou Qingshan reservoir dam breach by BREACH and FLDWAV under two conditions that initial caculating water level were respectively 34.30 m and 37.20 m during 10 000- year flood, then defined main factors of loss of life and applied the method given by Grahamto estimate loss of life, finally assessed estimation results and put forward non- structural measures to reduce loss of life.