Soil and water loss can cause the depletion of land resource and the degradation of eco-environment in many areas of China, which is the main reason of the reduction of local agricultural and industrial productivity. The process of soil infiltration has a major impact on the effect of soil and water conservation. To research how ryegrass influence the effect of soil and water conservation, the experiments in the conditions of different rainfall intensities, slopes and vegetation coverages (0, 20%, 40%, 60%, 80% and 100%) with the method of simulated rainfall were conducted. The results showed that: slope, rainfall intensity and vegetation coverage had a significant impact on the process of soil infiltration, the cumulative amount of water infiltration increased with the increase of vegetation cover, existing a significant positive correlation. The vegetation coverage also had an obvious influence on the model parameters of Kostiakov infiltration model, the parameter K increased but the parameter a decreased with the increase of the vegetation coverage of ryegrass. The change trend was the most notable in 30 mm/h rainfall intensity.