Based on the field investigation in August 2001 and August 2002, digital China Vegetation Map in 2001 and Qinghai-Xizang(Tibet) Plateau Vegetation Regionalization Map in 1996, vegetation characteristics along two sides of Qinghai-Xizang highway and railway are studied in this paper. Meanwhile, the impact of Qinghai-Xizang highway and railway constructions on the vegetation types are analyzed using ARCVIEW, ARC/INFO and PATCH ANALYSIS. It was found that:1) Qinghai-Xizang highway and railway span 9 latitudes, 12 longitudes and 6 physical geographic regions (East Qinghai and Qilian mountain steppe region, Qaidam mountain desert region, South Qinghai-Xizang alpine meadow steppe region, Qiangtang alpine steppe region, Golog-Nagqu alpine shrub meadow region and South Xizang mountain shrub steppe region);2) the construction of Qinghai-Xizang highway and railway destroyed natural vegetation and landscape, especially in 50m-wide buffer regions along both sides of the roads, it was estimated that the net primary productivity deceased by about 30 504.62t/a and the gross biomass deceased by 432 919.25-1 436 104.3t. The losing primary productivity accounted for 5.70% of the annual primary productivity within 1km-wide buffer regions (535 005.07-535 740.11t/a), and only 0.80%-0.89% of that within 10km-wide buffer regions (3 408 950.45-3 810 480.92t/a). The losing gross biomass was about 9.47%-17.06% of the gross biomass within 1km-wide buffer regions (7 502 971.85-25 488 342.71t), and only 1.47%-2.94% of that within 10km-wide buffer regions (43 615 065.35-164 150 665.37t).