From February to March 2017, November 2017 to March 2018 and November 2018 to March 2019 we used the point count method to survey the sex ratio, habitat selection and foraging behavior of Mandarin duck (Aix galericulata) in water systems (Raohe River, Ganjiang River and Xiuhe River) of Poyang Lake, Jiangxi Province, China. We recorded 162 individuals and determined 141 by gender: the sex ratio was 1.07. There was no significant male bias (n = 141, p = 0.210). Habitat selection results indicated that Mandarin duck tended to choose habitat with vegetation cover (2.40 ± 0.84) on riverbanks, with shoal proportions of 8.00 ± 6.00%, water velocity of 0.16 ± 0.12m/s and wider river widths of 190.90 ± 113.80 m. The foraging habitats were far from sources of disturbance such as mine factory (2.70 ± 0.48), village (286.10 ± 168.97 m) and road (114.50 ± 105.01 m). Our study showed that riverbank vegetation (Z=-2.614, P=0.009), distance to village (Z=-2.859, P=0.004) and road (Z=-2.085, P=0.037) in the foraging habitats were significantly higher than in control plots, indicating that Mandarin duck clearly preferred habitats with higher vegetation cover remote from both village and road. Principal component analysis indicated that water flow speed, distance to village, river width, vegetation cover, distance to mine factory and shoal proportion were the main factors for habitat selection. The results suggested that safety was the primary factor in habitat selection. The main foraging method was up-ending (61.54%); the duration of each up-ending foraging behavior was 1.92±0.83 s and foraging frequency was 14.67±4.43 times/min. This foraging strategy may be determined by food distribution and morphological structure.