[Objective] This paper aimed to explore the dynamic change of water use and the adaptation mechanism of Itea yunnanensis to microhabitat

to provide the theoretical basis for ecological environment reconstruction in karst region by analyzing the relationship between sap flow velocity and soil water content.[Methods] Thermal dissipation probe(TDP) was used to measure the sap flow dynamics of Itea yunnanensis at two microhabitats of non-stony soil surface and stony gully in karst region from July 26 to August 1

2009. At the same time

soil water content was measured.[Results] Diurnal variation of sap flow displayed an irregular peaked curve

the peak velocity of sap flow occurred in daylight

the peak base of sap flow velocity was observed at night. The soil water content in the same depth gradually decreased with rate along time. The sap flow velocity of Itea yunnanensis and the soil water content had insignificantly positive correlation.[Conclusion] Though there were different sap flow velocity of Itea yunnanensis at the two microhabitats of non-stony soil surface and stony gully in karst region

it showed similar timeline responses under the two habitats. There was no obvious relationship between sap flow velocity and soil water content.