Seasonal drought is the key scientific problem which faced by agricultural sustainable development in the red soil hilly region of South China. Soil available water capacity is one of the key factors which evaluate the water supply capability of soil to plant. Thirty-four red soil samples were collected in Jiangxi Province. Soil field capacity, permanent wilting point, soil organic matter, soil bulk density, soil grain density, and soil texture(sand, silt and clay) percentage component were measured in the laboratory according to experimental criterion. These soil physical parameters were analyzed with principal component analysis. The statistical model between soil available water capacity and principal components was constructed, and the correlation coefficient is 0.87. Results show that regional red soil available water capacity can be calculated from soil physical. And it is feasible that large areas soil available water capacity can be estimated using principal component analysis and other statistical methods.