根据Ｐｈｉｌｉｐ与Ｖｒｉｅｓ提出的土壤中水热交换的耦合理论，建立了植物固沙区土壤水热运移的耦合模型，考虑了液态水和汽态水运移对温度的变化，分析了植物根系吸水对土壤水热交换的影响，给出了植物蒸腾量、土壤蒸发量、根系汲水率及土壤表面热通量等有关变量的计算公式．利用本模式并采用具有二阶精度的Ｃｒａｎｋ－Ｎｉｃｏｌｓｏｎ格式对非线性扩散方程进行离散，对沙坡头植物固沙区土壤水热交换过程进行了数值模拟，模拟结果和实测值进行了比较，总体上符合较好，证明本模型具有实用价值，可为改造沙漠提供科学依据 According to the coupled theory of water and heat exchange in soil proposed by Philip and Vries, a coupled model of soil water and heat transport in sandy sand fixation area was established. Considering the changes of temperature under the transport of liquid water and steam, Water heat exchange, the formulas for calculating the relative variables such as plant transpiration, soil evaporation, root water uptake and soil surface heat flux are given. By using this model and using the Crank-Nicolson scheme with second-order precision, the nonlinear diffusion equation is discretized to simulate the soil water-heat exchange process in sand fixation plant. The simulation results and measured values ​​are compared. Generally, In line with the better, this model has proved to be of practical value, which can provide a scientific basis for the transformation of the desert