We analyzed the population fluctuation of Oriental White Stork (Ciconia boyciana) in Poyang Lake National Nature Reserve in winter from 1984 to 2011,and its correlation with climate variables and water level variables. The mean number of the Oriental White Storks in Poyang Lake National Nature Reserve was 1296 177. This population exhibited an obvious annual fluctuation,but as a whole showed a significant linear increase trend. The population size of Oriental White Stork in Poyang Lake National Nature Reserve was significantly negatively correlated with the annual lowest water level,the mean water level of October,and the mean water level of December,which maybe result from the decrease of available habitats and increase of human disturbance with the increase of water level in winter. This population trend in the reserve was also significantly correlated with the average minimum temperature of November. The Oriental White Stork mainly arrived at the Poyang Lake in November,and a proper temperature in this period may increase the food resource availability for Oriental White Stork,speed up energy recovery after long distance migration,and decrease their energy consumption for basal metabolism. The results derived from stepwise linear regression indicated that the average minimum temperature of November,the duration of high water level of January of the previous year,and the duration of high water level of July of the previous two years were significant predictors of the population trend of Oriental White Stork,which in total accounted for 78. 3% of the population fluctuation during 1984 - 2011.