The change in value of ecosystem services in Xilin River Basin was studied using the ways that Costanza et al evaluated ecosystem services.The result showed that from 1987 to 2000, the total value of ecosystem services in Xilin River Basin decreased by 31.6%.Of all the ecosys-tems,the ecosystem services value of grassland dropped to 4.38×10⁸$ from 5.13×10⁸$;the ecosystem services value of wetland dropped to 0.9×10⁸$ from 2.62×10⁸$,and that of cropland rised to 0.03×10⁸$ from 0.01×10⁸$. Among the total value of grassland ecosystem services,the ratios of F.sibiricum steppe,S.baicalensis steppe,A.lymus + bunchgrass steppe and A.lymus + forbs steppe decreased from 1987 to 2000 and those of S.krylavii steppe and Ar.frigida steppe increased,indicating clearly that the steppe ecosystem in Xilin River Basin is degenerating seriously.It was concluded that the decline in value of ecosystem services in Xilin River Basin was resulted from the degradation of ecosystems and the decrease in area of the natural ecosys-tems.