Soil physical characteristics and its spatial variation were studied in Pailugou watershed located in Qilian Mountains Forest Ecology Monitoring Station belonging to the State Key Field Scientific Experimental Station. Results showed that (1) Soil physical characteristics changed with soil depth and the change extent was in the order of sub-alpine shrub meadow soilforest gray-brown soilchestnut soil. (2) Total soil porosity varied dramatically with different vegetation types. The total soil porosity of sub-alpine shrub meadow soil was higher than forest gray-brown soil,and in turn,chestnut soil. There was no significant difference in soil capillary porosity under different vegetations. For soil non-capillary porosity,there was significant difference among chestnut soil,sub-alpine shrub meadow soil,and forest gray-brown soil from the viewpoint of geographical spatial difference (P0.05). (3) The soil water holding capacity of forest gray-brown soil was higher than sub-alpine shrub meadow soil and chestnut soil. As for soil capillary capacity,sub-alpine shrub meadow soil was the highest,followed by forest gray-brown soil and then chestnut soil. Soil non-capillary porosity varied dramatically with different degrees of vegetation cover. As for natural moisture content,sunny slope is significantly different among all vegetation types. Sub-alpine shrub meadow soil is the highest,followed by forest gray-brown soil and chestnut soil. Sub-alpine shrub soil had good structure and texture and greater potentiality for water conservation. Natural moisture content of all the soil types was increased with elevation.