To investigate the variations in temperature and humidity of the marginal soil on the southern side of a greenhouse during the winter in a cold, arid region of northern China, four linings were compared: an unlined (control) structure, a 5 cm-thick polystyrene extruded board buried at a depth of 60 cm, a 5 cm-thick polystyrene extruded board buried at a depth of 30 cm, and 5 cm-thick cement blocks buried at a depth of 30 cm. In addition, a computational fluid dynamics (CFD) method was used to simulate the soil temperature and humidity in the test area. The results showed that the relative error between the simulated and measured soil temperatures for different linings was less than 10%, the absolute error was 0.06 to 0.49 degrees C, the relative error of soil moisture contents was less than 1.2%, and the simulation results were more accurate. The linings blocked water and heat movement inside and outside the greenhouse. In summary, we provide a theoretical basis and experimental reference for methods of thermal insulation of marginal soil on the southern side of a greenhouse. To save engineering and material costs, it is recommended to bury a lining of extruded polystyrene boards at depths of 30 and 60 cm when planting shallow-rooted and deep-rooted crops in the greenhouse, respectively.