Abstract: Objective To investigate the age-related changes in motor function’spontaneous activity and cognitive function of C57BL/6N mice. Methods Different aged, include 3,6,12,16 and 20 months old, groups of mice was constituted. Both rolling-bar test and pole-climbing test were performed to assess motor function. A computer-aided device was applied to rating spontaneous activity, and step-down test to evaluated the passive avoidance memory. Results 6 months old group of mice have significant longer rolling bar test latency than those of other groups (P＜0.05) and also manifest a shortest pole-climbing time (P＜0.05). 6，12 and 16 months old groups show a significant more spontaneous activity than those of other groups (P＜0.01). There is an age related decline in the performance of step-down passive avoidance test. Conclusion The age-related changes of motor function, spontaneous activity and cognitive function of C57BL mice have different patterns during ageing.

Key words: Mouse, Behavior, Aging