In order to improve flood water utilization rate during flood season, a real-time dynamic operation of reservoir water levels called improved pre-storage & pre-discharge method is presented, in which real-time information of flood, rainfall, engineering and short-term flood and rainfall forecast issue is studied synthetically. Through its application to Huanren Reservoir and gradient reservoir group, and compared with the originally designed flood operation of reservoir, the results show that the real-time dynamic operation method based on integrated information can increase hydropower generation without increasing flood risk. The method is feasible and practical, and it can also be applied to other reservoirs, especially to the large-scale reservoir or hydropower station for real-time operation in the water shortage region of North China.