Abstract: Three years field experiments show that corn straw mulch had great effect on soil temperature, soil water and crop yield. It can decrease the maximum soil temperature, increase the minimum soil temperature and decrease the swing of soil temperature at daytime and night. The soil temperature of mulching treatment is higher than CK in winter, but in spring it can decrease the soil temperature, this effect of low-temperature in spring postpones wheat growth periods. The 0～10 cm deep soil temperatures of less mulching(LM) and more mulching(MM) are 0.3℃/d and 0.58℃/d higher than CK in winter and 0.42℃/d and 0.65℃/d lower than CK in spring. Straw mulching can restrain soil evaporation effectively. The soil evaporation of LM and MM treatment decreased by 21% and 40.4% compared with CK. The wheat yields of LM and MM decreased by 4.1% and 10.4% compared with CK due to the low-temperature of straw mulching.