Abstract: Based on the basic principle of Smoothed particle hydrodynamics (SPH), this paper tries to calculate numerically the unsaturated soil moisture-heat coupling problem. Firstly, the parabolic partial differential equations were solved by programming based on SPH algorithm, and then a comparison was made with analytic solution. The calculation results show that SPH algorithm used for the numerical simulation of parabolic partial differential equation is feasible and effective; it provides a theoretical basis for the calculation of moisture migration problem under the action of temperature in the unsaturated soil. Then, the numerical calculations of heat transfer and moisture migration were carried out in unsaturated soil. Considering the difference in thermal diffusion coefficient, moisture diffusion coefficient caused by temperate, moisture diffusion coefficient and heat source, the paper investigated the distribution characteristics of moisture and temperature by number simulation, and the process and mechanism of moisture-heat evolution was analyzed, thus the application scope of SPH was extended.