[Objective] The impacts of biochar on the physicochemical properties and hydraulic characteristics were assessed in order to guide the improving of the red soil at uplands.[Methods] Soil bulk density and porosity were measured for samples of two different layers of undisturbed red soil treated with varying amount of biochar, and curve of soil water characteristics were studied by pressure membrane method.[Results] Application of biochar could significantly decrease bulk density as well as improve porosity and soil organic carbon content. With the increase of application amount, soil bulk density decreased; While porosity and soil carbon content increased gradually. Soil saturation moisture content, field capacity and available water content increased and wilting coefficient decreased with the increasing application of biochar. The saturated moisture content, field capacity and available water content were at their highest when the application biochar was 30 t/hm². The application amount of biochar was significantly and positively correlated with soil saturation moisture content, field capacity and available water content, and had significant negative correlation with wilting coefficient.[Conclusion] Application of biochar can significantly increase field capacity and available water content of red soil.