To explore the effect of litter mulch on preserving soil water and its mechanism in red soil sloping-land, in situ experiments were conducted in sloping-land of red soil derived from Quaternary red clay in De’an County in northern Jiangxi Province, the effects on soil water retention capacity, soil water supplying capability and soil water availability of the 0—60 cm soil layer was studied after the litter mulching measure had been implemented for 15 years, with the bared slope being used as the control. The results showed that soil water retention capacity of red soil in northern Jiangxi Province was low, water supplying capability was weak, and soil water availability was low, i.e from 9.0% to 11.1%. The water retention capacity of the upper layer of the soil (i.e. the soil within 0—30 cm depth) on the red soil slope was higher than that of the bared slope. The water supplying capability of the lower layer of the soil (i.e. the soil within the 30—60 cm depth) of the red soil slope with litter mulch was higher than that of the bared slope when the soil water suction was less than 100 kPa. Litter mulch effectively increased the soil water retention capacity of the red soil, especially for the upper layer, and also enhanced the water supplying capability of the upper layer of the soil under relatively wet conditions, but had relatively weak effects on soil moisture availability. The results of this study can provide guidelines for the optimization of the surface mulching measures of sloping cropland, increasing and maintaining soil water resources, and reasonable exploitation and utilization of red soil slopes in southern China.