Population dynamics and gamogenesis of Daphnia magna from Huaihe River were studied under four temperatures (15, 20, 25, 30℃) and three food concentrations (1×104, 1×105, 5×105 cells ml-1). During early days of experiment, population density of D. magna increased continuously, and it presented a trend of decrease or stabilization after it reached the density peak. Maximal instantaneous increase rate occurred at 15℃ under middle food concentration (1.36 d-1), while appeared at other temperatures under high food level (20℃: 1.51 d-1; 25℃: 1.39 d-1; 30℃: 0.69 d-1). At same temperature, the maximal population density (MPD) of D. magna were significantly positively correlated with food concentrations (p<0.01). At same food concentration, first brood time (5-21 d), the time reaching MPD (15-29 d) and the body length of D. magna at first reproduction (1.75-2.67 mm) decreased with increasing temperature. The more resting eggs were observed in the combinations of middle food concentration and low temperatures (15℃: (16.7±2.5) ind.; 20℃: (18.3±3.8) ind.). No resting eggs/ephippia occurred at 30℃. Males occurred in all combinations except the combination of 15℃ and middle food level. Male density and population density of D. magna were significantly positively correlated 25 days after the beginning of the experiment (30℃: p<0.05; 15-25℃: p<0.01). Our results suggested that the formation of resting egg/ephippium and male of D. magna was affected by temperature, food level and population density, and lower temperature was main inducement.