In order to investigate the behavior of the coupled heat and moisture transfer of the ground surface in north-south direction for sunlight greenhouse, an actual greenhouse was taken as study object to test the variation of soil temperature and moisture, the intensity of radiation and temperature and moisture of air. The results show that for either the condensation process in night or the evaporation process in day, the middle surface has the biggest gradient in soil temperature and humidity and the largest heat transfers, soil moisture significantly decreases because of evaporation during 8:00-18:00 period in day; soil moisture significantly increases. When condensation occurs during 18:00-8:00 of the next day.