Abstract: TTaking 15-year-old ‘Liaoning 1’ walnut trees as test material, we studied the effect of straw mulching (SM) on changes of soil water temperature, organic matter content, root growth and fruit yield and quality of walnut orchard in northern dryland. The results showed that: straw mulching could increase soil temperature at lower air temperature and decreased soil temperature at higher air temperature; moreover, straw mulching could effectively improve the soil moisture content at 0-40 cm, and significantly increased the soil organic matter content at 0-60 cm soil layer; compared with CK, straw mulching increased the length and surface area of the fine roots of the 0-60 cm soil, and significantly increased the oil content and yield of the fruit. Therefore, the appliance of SM in the walnut orchard has the effect of storage and preservation of soil moisture and increase the soil fertility, in order to improve the fruit yield.