Abstract: The effect of vertical temperature gradient in the unsaturated zone on the moisture content movement cannot be neglected in an arid and semi-arid region.In order to quantitatively study the water migration under temperature change,a hydrothermal coupling model is established,in which the determination of thermal parameters become an key and difficult problem.Based on the measured data and a detailed analysis of them,a new model is proposed,in which the moisture content is considered as a independent variable and used to calculate thermal conductivity,terms of saturated thermal conductivity and residual thermal conductivity.Through the analysis and verification of its reliability,solution method and the sensitivity,we can conclude that this model can conveniently calculate thermal conductivity of hydrothermal coupling.It can be solved by several kinds of methods and it is of good practicability and high fitting accuracy.