Gullies are extensively distributed in the upper Yangtze river Basin,SW-China.But the development of these gullies is still not clear because there is no a reliable technique to be used for quantifying this issue.The objective of this study is to investigate the distribution characteristic of gully system and major factors affecting gully development in Changshanling area of Xichang,using GPS and GIS.We measured the gully system using RTK-GPS and established digital elevation mode(DEM) of the gully catchment,and proposed a method forextract gully system from the established DEM in frame of GIS.Our results indicated that our method for quantifying gullies from the DEM based on RTK-GPS survey is practical and effective.The gully density in Changshanling catchments was 46.7 m/hm~2,and annual average gully erosion amount was 191.9 t/hm~2,indicating a severe soil erosion and land loss in SW-China.Therefore,soil and water conservation measures should focus on controlling gully erosion for rebuilding ecological environment in the study area.