[Objective] The effects of green manure on soil physical properties of dryland winter wheat field were investigated in order to provide scientific basis for its popularization in dry farming area of Loess Plateau. [Methods] Based on a 4-year winter wheat field experiment, the effects of planting Changwu soybean, Sudan grass, soybean/Sudan grass mixture and control with no cover crop (CK) on bulk density, porosity, water holding capacity, and aggregation in the cultivated soil layer at 0—20 cm depth during the harvest of dry winter wheat were studied in the Loess Plateau. [Results] At 0—10 cm depths, compared with CK, Sudan grass and mixture treatment significantly decreased soil bulk density. Soybean, Sudan grass and mixture treatment significantly increased soil capillary porosity, total porosity, saturated water capacity, capillary water holding capacity, the proportion of large aggregates (＞ 5 mm), and aggregate mean weight diameter (MWD) (p＜0.05). At 10—20 cm soil depth, Sudan grass treatment had the higher proportion of large aggregates and MWD than CK. Soil bulk density was negatively correlated with soil organic carbon, while soil total porosity, saturated and capillary water capacity were positively correlated to cover crop biomass and soil organ carbon. [Conclusion] In the Loess Plateau, top soil physical properties can be enhanced by monoculture planting Changwu soybean, Sudan grass, or mixture sowing during summer fallow, especially monoculture of Sudan grass.