Objective： To explore the effect of undenatured type Ⅱ collogen （UCⅡ） on the motor function in aging db/db mice. Method： db/db mice fed all the life were randomly divided into model， UCⅡ intervention， and positive control groups， while， db/m mice and youth db/db mice were used as the normal control group and youth control group. After intervention for 12 weeks， crawl activity and catwalk index were estimated. And then 4 weeks later， the bone histomorphometry index as well as musculus gastrocnemius were measured. The results showed that the gastrocnemius muscle index in UCⅡ intervention group was 0.44%， which was significantly higher than that in the model control group（P < 0.05）， and the bone mineral density was 439.11 mg/cm3 in the UCⅡ intervention group mice， which was significantly higher than that in the model， normal and positive control groups（P < 0.05）， the trabecular bone volume and trabecular bone number in UCⅡ intervention group were significantly higher than that in the control and youth control groups （P < 0.05）. The crawl time in UC Ⅱ intervention group was longer than that in the model and positive control groups（P < 0.05）. Compared with the model control group， the stride， swing speed， speed， pace and regularity index in the UC Ⅱ intervention group were increased， while the swing phase and duty cycle decreased. Moreover， there was a positive correlation between the gastrocnemius index and the duty cycle， the crawling time（P < 0.05， coefficient > 0.5）， and a certain positive correlation between the bone mineral density and the crawling time， the duty cycle and the swinging speed （coefficient > 0.5）. Therefore， UC Ⅱ could increase gastrocnemius and bone density， improve motor function of aging db/db mice.