Abstract: Abstract: Concerning the decline of crop yield caused low temperature under no-till with straw mulching in dry farmlands of north China, field experiments were conducted to investigate the effects of plastic mulching on the surface of no-till with straw mulching on soil water and temperature at the Ministry of Agriculture Shouyang Dryland Agriculture Key Field Scientific Observation and Experiment Station. The field management practices including conventional tillage (CT), no-till with straw mulching (NTSM) and plastic mulching on the surface of no-till with straw mulching (NTSMP) were designed to study their effects on soil water and temperature, water use efficiency (WUE) and crop yield. The results showed that the maize (Zea mays) was able to take a good advantage of soil water in the deep layers in the treatment of NTSMP than in treatments of CT and NTSM in the seeding stage under less rainfall condition. In the early growth stage of maize at the topsoil (0-20 cm), the soil water content in the treatment of NTSMP was 20.2% and 21.5% higher (p<0.05) than that of NTSM and CT, respectively. However, the water content in NTSMP treatment was 8.8% to 14.0% and 12.7% to 18.8% lower (p<0.05) than that in the treatments of NTSM and CT, respectively. The soil water storage declined in the treatment of NTSMP at the end of growing season, but it was not significant (p>0.05) compared with the treatment of CT. This might attribute to the good water conservation capacity of the soil interface in NTSMP that allowed the use of water from deeper soil layers. The treatment of NTSMP had significant (p<0.05) effects on soil temperature mostly in the seeding stage and in the decline stage when the crop area covering the soil was smaller than in any other stages. However, the effects soil temperature on the growth of crops was more important in the earlier stages than in middle and late stages. The average soil temperature in NTSMP treatment in the 0~10 cm deep soil layer in the early growth stage of maize (April, May) was 3.2℃ and 1.9℃, higher than that of NTSM and CT, respectively. The yield of maize in the treatment of NTSMP was 50.3% and 36.8% higher than that in treatments of NTSM and CT (p<0.05). The water use efficiency increased by 42.5% and 30.4%, respectively, compared with the treatments of NTSM and CT. Therefore, it can be concluded that the treatment of NTSMP increased the soil surface temperature and water use by maize in the early growth stage. The NTSMP treatment provided a better water and temperature condition for maize growth. Thus, the method can improve maize yield and the water use efficiency.