Abstract: In order to understand the effects of film mulching on water retention and temperature changes in different soil depths of loess soil, the sinusoidal model and fitting equation were used to analyze the soil temperature changes quantitatively under colorless film mulching, black film mulching and no film mulching.The results showed that soil moisture and soil heat capacity were with the largest values at the depth of 40 cm, while the lowest values were at 10 cm at 0:00~8:00 a.m., respectively.The soil temperature under the black film mulching was generally higher than that of the colorless film mulching, with better heat holding capacity during night time.At 8:00 a.m.~16:00 p.m., the soil temperature under the colorless film mulching increased quickly and the soil temperature peak appeared about 1h earlier than that of the black film mulching.The shallow soil (0~20 cm) temperature increased quickly but decreased quickly as well and its temperature amplitude change was larger than that of the deep soil (20~40 cm).The effect of film mulching on soil temperature was not significant with the increase in soil depth.The colorless film mulching and black film mulching significantly increased soil water content, soil temperature and soil heat capacity.The colorless film mulching is with a better heating effect than that of black film mulching; and the soil temperature amplitude changes in an order of colorless film mulching >no film mulching >black film mulching.