Objective To explore the differences in physical activity, sedentary behaviour and balance ability between older adults and young people, and the correlation of physical activity at different levels and sedentary behaviour with balance ability. Methods A total of 74 older adults and 60 young people were selected. The physical activity and sedentary behaviour of the subjects were monitored by three-axis accelerometers, and their static balance ability was measured by three-dimensional (3D) force platform. Results For elderly women, moderate-to-vigorous physical activity (MVPA) were positively correlated with static balance ability (P<0.05), and sedentary time was negatively correlated with static balance ability (P<0.05). For elderly men, sedentary breaks were positively correlated with static balance ability (P<0.05). Conclusions Compared with young people, older adults have higher light physical activity levels and less sedentary time. For older adults, especially elderly women, those with higher MVPA levels or less sedentary time have better static balance ability. Physical activity has a positive effect on balance control.