Interspecific relationship of habitat use by Takin(Budorcas taxicolor) and Serow(Capricornis sumatraensis) was studied in South East Tibet,China between December 2001 and July 2002.A total of fourteen transects were set randomly along Cibagou Valley in the Cibagou National Nature Reserve,and 187 sample plots(10 m×10 m) were set every 250 m apart from the bottom to top position of the transects,the vegetation types of plots were recorded,and other 9 habitat quantitative parameters of them including altitudes and slops,etc,were also measured.We have also checked if there were new tracks of Takin or Serow in winter,spring and summer,respectively.Vanderploge and Scavia's selectivity index was used to assess Takin and Serow's habitat selection and found that Takin mostly preferred fargesia-coniferous forests while Serow mostly preferred fargesia-coniferous forests in winter.A discriminant analysis for 9 quantitative factors showed there was no significant difference between the habitat selection of Takin and Serow.In spring,Takin most preferred fargesia-coniferous forest,followed by broad-conifer mixed forest while Serow preferred theropencedrymion mostly,followed by fargesia-coniferous forest;the discriminant analysis for 9 quantitative factors showed significant differences between Takin and Serow,and the interspecific differences in selection on slope degree,slope aspect and distances from water were most significant.In summer,Takin mostly preferred Alpine meadow-shrubs,while Serow mostly preferred theropencedrymion,followed by fargesia-coniferous forests and rhododendron-coniferous forests;the discriminant analysis for 9 quantitative factors showed significant differences between Takin and Serow,and the interspecific differences in altitude,shelter,cover canopy,arbor density,bamboo density and vegetable type were most significant.Their coexistence mechanism and reasons for differentiation were discussed through food,behavior and other aspects.