The common crane Grus grus is currently listed in the Second Category of National Key Protected Wildlife Species in China and the second appendix of CITES with a global population size estimated at 360000-370000 individuals. In China there is a wintering population of 10000-12000 individuals, of which 8408 individuals are found at Poyang Lake, which represents an important wintering habitat for the species in China. From November 2013 to February 2014, the wintering time budget and foraging behavior of common cranes inhabiting rice fields of Poyang Lake were observed by instantaneous scan and animal focal sampling methods. Common cranes spent most of their time foraging (64.09%), followed by alerting (15.97%), flying (8.67%) and maintenance (7.37%) behaviors. While foraging behavior increased over early, middle and late wintering stages, the other behaviors gradually declined over the same time period. There was a significant interaction effect among environmental factors on behaviors. Maintenance behavior changed most obviously with environmental factors. For example, an increase in maintenance was observed when daily minimum temperature increased, daily maximum temperature decreased, day length increased and humidity decreased. Foraging behavior increased when day length increased and humidity decreased; and alerting behavior increased when day length increased and humidity decreased. The effect of environmental factors on adult individuals was the same as the overall pattern. There was only one significant impact on the foraging behavior of juveniles. In other words, when day length increased and humidity decreased, the foraging behavior of juveniles increased. The impact of environmental factors on behavior may be a nonlinear relationship that results in the influence trends changing in different ranges. In terms of the activity rhythms, foraging behavior was always kept at a high level in each daytime period, peaking at 11:00-11:59 and 17:00-17:30. Because the foraging habitat and communal roosting habitat of common cranes were separated, the foraging peak in the morning was delayed. There was also a large difference in activity rhythms between adults and juveniles, with foraging behavior of juveniles being higher than adults in each observation period. Mean peck rate was (32.06± 0.47) pecks/min, mean step rate was (6.55± 0.35) steps/min, and there was a significant negative correlation between peck rate and step rate. A significant interaction effect between time and group types was found on peck rate. Because the availability of food resources in rice-field habitats decreases gradually over winter, the peck rate of cranes should also decrease gradually over time. To ensure adequate energy supply during the winter, it is likely that common cranes would change their foraging strategy by increasing the step rate and foraging time. Nearly (1.37±0.04) times and (6.02±0.37) s per unit with interval were used for alerting. Adults spend more time alerting than do juveniles and spend more time alerting when in family groups than in flocks. This paper also provides scientific suggestions for the conservation of this species.