Abstract: The paper studied on comprehensive appraisal of dynamic change of the ecosystem service function value in loess plateau in northern Shaanxi province using 3S technologies. The results showed : the ecological services value in loess plateau in northern Shaanxi province was 46.723 billion yuan in 1978, the ecological services value in 1990 was 57.703 billion yuan, and the ecological services value in 2000 was 56.099 billion yuan. From 1978 to 1990 , the ecological services value rise by 19.03%, and from 1990 to 2000 drooped by 2.86%, but in the entire 22 years ecological value in northern Shaanxi province increased by 16.71%. Ecosystem services in loess plateau in northern Shaanxi province have the spatial distribution: on large regional terms, from 1978 to 2000, ecosystem services value in northern Shaanxi province slowly increase, and its increasing mainly in the south ,but in the north changed little. But it is noteworthy that although the general trend is slowly increasing, but the reducing of the ecosystem services value in local area was very keen. From 1990 to 2000 ecosystem services value in northern Shaanxi province is declining. Improvement of the ecological environment was regional disparity, but the northern region improved larger and the southern region improve slowly.

Key words: Ecological services value, loess plateau, spatial analysis, landuse