Diurnal activity budgets and rhythm of wintering Bar-headed Geese (Anser indicus) at Caohai Lake were studied with instantaneous scan sampling methods from December 2011 to February 2012. During the wintering period, the major behaviors were foraging and resting, which accounted for 50.48% and 43.79% respectively. There were two foraging peaks, one in the morning and the other in the late afternoon, and one resting peak in the noon. Foraging, resting and drinking had significant differences among different segments of time during a day. The geese spent most time in foraging on the land, while resting in the shallow water. It is suggested that the activity patterns in different types of habitat were influenced by food abundance and human disturbance. Partial correlation analysis showed that temperature was the main factor influencing the diurnal activity patterns of Bar-headed Geese. As the temperature rises, the geese decreased foraging and increased resting.