Based on the 1976, 1989, 2000 and 2005 remote sensing images and related meteorological data, the landscape pattern change and its ecological effect in Manas River Basin of Xinjiang in 1976-2005 were analyzed with GIS and FRAGSTATES. In the study period, the landscape pattern change in the Basin mainly manifested in the increase of farmland, grassland, and residential area while the decrease of forestland, wetland, desert, and snow and ice coverage. At landscape level, the patch number, landscape shape index, and contagion index increased, while Shannon's diversity index decreased; at class level, there was a greater difference in the heterogeneity index among different kinds of landscape, indicating a complexity of the landscape ecosystem. The landscape pattern change caused the negative ecological effect of wetland area shrinking, but some positive effects such as the decrease of evaporation and the increase of relative humidity. From 1976 to 2005, the wetland area decreased from 415.7 km2 to 297.4 km2, with a decrement of 28%, evaporation decreased by 0.91 mm x a(-1), and relative humidity increased by 0.037% x a(-1).