Abstract: In this paper, based on the experimental data of maize, sunflower, Acacia confusa and Leucaena glauca under various treatments of air and soil temperature as well as soil water content, the effects of soil water content and temperature on plant root hydraulic conductivity (LR) were analyzed. The results indicate that LR in 40/30℃ (day/night air temperature) was larger than that of 30/25℃ air temperature when soil moisture was suitable for plant growth. When root water stress was very serious, i.e. the root water potential was lower than -1.5 and - 2.0 MPa for Acacia confusa and Leucaena glauca respectively, the LR in 30/25℃ air temperature was larger than that of 40/30℃ air temperature. And also the root hydraulic conductivity increased with soil temperature(Ts) increasing when Ts was lower than 35℃ for sunflower and 30℃ for maize growing season. When Ts was higher than that values, LR would decrease with temperature increasing continuously. LR increased quickly when root was rewetted after it was encountered soil-drying process. LR would reach the values before soil-drying, after 1.5 days and 3 days rewetting to Leucaena glauca and sunflower respectively. After that, it was larger than that before soil-drying. The changes of root hydraulic conductivity during soil-drying process and after rewetting were similar to the change process of root water potential.