Abstract: To better understand stable isotope enrichment and metabolism of small mammals and to provide alternative for their dietary information analysis,a controlled feeding experiment was conducted on plateau pikas (Ochotona curzoniae) with mixture of flours of corn (C4 plant),millet (C4 plant) and mung bean (C3 plant).Muscles of back legs were collected from plateau pikas for stable isotope analyses after 40 days artificial feeding.The results demonstrated that stable carbon and nitrogen isotopes showed great variations after introduction of artificial food.Stable carbon isotope ratios of treatment groups became less negative compared with the control (-19.05±0.09)‰ to (-24.66±0.42)‰］ and showed great differences (t=-31.528,df=6,P=0.000).Stable nitrogen isotope ratios of treatment groups were a little bit positive compared with the control ［(3.61±0.32)‰ to (3.28±0.13)‰］ (t=1.427,df=7,P=0.197).Fractionations of stable carbon and nitrogen isotopes between plateau pikas muscles and their diets were 4.73‰ and 2.79‰ respectively.Introduction of C4 food had strong effect on stable isotope metabolism (especially for stable nitrogen isotope) of plateau pikas.Turnover rate of stable carbon and nitrogen isotopes for plateau pikas might be much more than forty days as respected.