Salt absorption, transpiration induced water uptake and the radial reflection coefficient of the root system of arrowleaf saltbush (Atriplex triangularis) were measured in order to analyze ultrafiltrational characteristics of its root system in relation to salt tolerance of the plant. Results show that increase in salinity stress in the root environment resulted in increase in Na⁺ uptake, and decrease in transpirational water uptake and in radial reflection coefficient as well. However, the relative amount of Na⁺ uptake based on the salt concentration of the solutions from root bathing showed a tendency of declining with the increase in salinity stress. The amount of Na⁺ being taken into the xylem did not exhibit any significant increase with the decreasing radial reflection coefficient of the root. This indicated that arrowleaf saltbush was able to change the ultrafiltration characteristics of its root system and reduce radial reflection coefficient of the root, thus lowering the risk of higher xylem tension leading to xylem cavitation and able to reduce salt absorption to avoid damage of salt over-accumulation to the plant.