Effects of grass coverage degree (30%, 60%, 90%) and rainfall intensity (1, 1.5, 2, 2.5, 3 mm/min) on the soil infiltration process on the 15° grass slope were studied under simulated rainfall condition in the third subregion of loess hilly region. The results were as follows: (1)Soil infiltration rate increased with the increase of grass cover and rainfall intensity, while the soil infiltration rate increased significantly with the increase of grass coverage rate. The initial infiltration rate of soil and rainfall intensity presented exponential relationship. The soil stability infiltration rate and rainfall intensity showed the power function relations. (2)The cumulative soil infiltration and rainfall time had a good power function relationship. The cumulative infiltration of soil increased significantly with the increase of grass coverage rate. The effect of rainfall intensity on soil cumulative infiltration showed phase-based difference. (3)The increase of grass cover could significantly increase the soil infiltration coefficient, the soil infiltration coefficient decreased with the increase of rain intensity. Under the coverage of field grass (about 60%), the effective rainfall intensity of grass cover in increasing soil infiltration coefficient was between 1～1.5 mm/min. (4)The relationship between soil infiltration rate and rainfall time was fitted by four infiltration models, and the Horton formula was found could well simulate the soil infiltration process.