Muddy water with high concentration often occurs in rainstorms on the Loess Plateau,which directly influences runoff and sediment yield on slope. Know ledge of muddy water infiltration with different concentrations is important to the study of soil erosion on slope. By taking clean water as control, infiltration characteristics,infiltration processes,and infiltration decay ratio of muddy water with different concentrations were measured. Results showed that the infiltration rate at the end of first second, the stable infiltration rate,and the cumulative infiltration amount decreased exponentially with mud concentration, while the infiltration decay ratio increased logarithmically with mud concentration. The two relationships appeared steady as mud concentration increased. In the same time interval,the cumulative infiltration amount of clean water was always the highest,but decreased as mud concentration increased. Muddy water had a decreasing effect on infiltration.