Abstract: The object of this paper is to determine the annual and emergency water diversion scale of the river around Wuwei County considering the amount of water needed to maintain the water ecological environment and the landscape water level.The MIKE21 model was used to calculate the water scale required under different conditions,and the Tennant method was used to calculate the ecological water requirement.The results showed that water quality of the river could reach its water quality target as the Class IV among the high,median and low flow years when the diversion flow rate was 2 m³/s,and the water quality could be improved from poor V class to IV class within 6 day when the diversion flow rate was 4 m³/s.The ratio of time that the diversion flow could reach 2 m³/s by regulation of gate was 94.5%,81.4% and 59.2% of high,median and low flow years,and the ratio of water diversion to water supply was 58.6%,68.8% and 71.7%,respectively.