The effects of soil water availability and the days after budbreak on the root hydraulic conductivity in Haloxylon ammodendron sapling with potted plants was quantitatively analyzed. The results showed that the entire root hydraulic conductivity of Haloxylon ammodendron sapling increased linearly with soil water availability and the days after budbreak; the root hydraulic conductivity per unit root surface area of Haloxylon ammodendron sapling increased at first and then decreased according to parabola with soil water availability, and the root hydraulic conductivity per unit root surface area of Haloxylon ammodendron sapling decreased linearly with the days after budbreak. The obtained quantitative relationships between root hydraulic conductivity of Haloxylon ammodendron sapling and soil water availability and the days after budbreak can be applied to the research of root water uptake dynamic models and the research of plant water transfer. 