A field test was conducted at the Mizhi Experimental Station of Northwest A & F University from October 2014 to April 2015, to research the soil moisture movement law and temperature difference under different plastic film mulching in plant dormancy period in semiarid loess hilly region. No plastic film mulching (CK) and transparent film mulching (TF) treatments were set up at the same level of terraces at the depth of 0-400 cm to observe soil moisture movement. Three treatments, including CK, TF, and black film covering (BF) were designed at the same level at the depth of 0-50 cm (15 cm, 30 cm, 50 cm) to observe soil temperature. The results showed that soil water storage capacity of TF was 51.9% higher than that of CK at the depth of 0-400 cm in the dormancy period, and the difference was significant (p < 0.05). The maximum amplitude of soil water storage appeared at the depth of 0-20 cm, and soil water storage at the depth of 20-60 cm decreased from 54.9% to 26.3%. In typical sunny days, the maximum temperature difference between the three treatments of CK, TF, and BF was 2.25-2.7 oC, 3.45-3.5 oC, and 1.5-1.8 oC at the non-freezing stage. Whereas the difference was 1.65 oC, 2.1 oC and 1.2 oC at the freezing stage, and the effect of film insulation was not obvious when the soil was frozen. The depth of film insulation was up to 15 cm, the warming effect of BF treatment was better than that of TF. The above evidences suggested that the plastic film mulching in plant dormancy period could increase soil moisture and soil temperature, reduce soil water loss and promote water deep infiltration in the 0-20 cm soil layer. Furthermore, BF treatment might be more favorable for warming and stabilizing temperature change than TF treatment.