[Objective] This paper aimed to investigate the mechanism of soil erosion resistance by vegetation restoration and the water stability index of red soil in Ganjiang river basin area.[Methods] Soil samples developed from three parent materials(the granite, red sandstone and quaternary red earth) under different vegetation coverage were selected, to explore the dynamic change of water stability by using hydrostatic balance method.[Results] The dynamic change of water stability of red soils decreased with soil immersion time in all samples. This decreasing trend was less in woodland and shrub land compared to bare land. Soil water stability in both woodland and shrub land improved significantly, compared to bare land developed from all the three parent materials.[Conclusion] The hydrostatic balance method is more suitable to study the dynamic change of water stability. Vegetation restoration is beneficial to the improvement of soil water stability in Gannan area.