Based on soil moisture data from September 2004 to April 2005

the dynamic change of soil mois- ture and the influence from a typical rainfall were analyzed under three types of landuse (cropland

grassland and black fallow) in the peak-cluster depression areas of karst region in Southwest Guangxi Province. Re-sults showed that soil moisture in surface layer (0-20cm) was the lowest

but fluctuated violently in all lay-ers. Down to deeper layers

soil moisture increased and became steady. Surface soil moisture of grassland was lower than that of cropland for the absorption and transpiration of grass.Soil moisture was obviously in-fluenced by typical rainfall

but the time responses for three types of landuse were different. Surface soil moisture increased obviously in cropland and grassland one day after rainfall

whereas bottom soil moisture reached the peak value 6～8 days after rainfall.Soil moisture of the 0-30 cm layer in black fallow reached the maximum 3 days after rainfall. The time stability of soil moisture in grassland was the worst.Precipitati- on

land use types (vegetation)

and soil texture were the main factors influencing soil moisture in the area.