Remarkable achievement has been obtained since the implementation of the Grain for Green project in China. Aiming to explore the improvement effect of restoration years on soil properties and infiltration performance and its mechanism, the water stable aggregate characteristics, root characteristics and infiltration rate of 30-cm-depth farmland and grassland soils with 5-year (C_{5 a}), 15-year (C_{15 a}) and 25-year (C_{25 a}) restoration in the Loess Hilly and gully area were measured. The factors affecting soil infiltration were analyzed. The results showed that the organic matter content (SOM), total nitrogen content and root traits of grassland soil with different abandoned years were C_{25 a}>C_{15 a}>farmland≈C_{5 a}. The mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D) of 0-30 cm soil aggregates and initial infiltration rate (IIR) and stable infiltration rate (SIR) were 0.78, 0.2 mm, 2.89, 7.80 and 2.58 mm/min for farmland; 2.03, 0.62 mm, 2.73, 6.36 and 3.21 mm/min for 5-year grassland; 2.25, 0.77 mm, 2.69, 11.12 and 4.33 mm/min for 15-year grassland; 2.44, 0.93 mm, 2.64, 13.67 and 5.93 mm/min for 25-year grassland, respectively. There was a significant positive correlation between soil SIR and SOM, bulk density and aggregate content of >5 mm (P<0.01). The improvement effect to soil of restoration continues to increase with the extending years of Grain for Green. Therefore, the existing achievements of Grain for Green should be maintained in areas with serious soil and water loss, and the manual intervention and management in the early (5-year) stage of restoration should be strengthened to realize its potential ecological value in the later stages.