Through indoor infiltration of clean water film hole irrigation and four different silt contend and four clay and sand grade of infiltration of muddy water film hole irrigation tests under the same condition, the influence of infiltration characteristics of muddy water film hole irrigation under different silt contend and clay and sand grades was studied. In the study eight different kind of muddy water were configured, four of them were different in clay and sand grades, but had the same silt content of 5%, and others were different in silt content that respectively by 2%, 5%, 7% and 9%. Soil dry density was 1.40 g/cm3. The effects of silt content and clay and sand grade on freedom infiltration characteristics of muddy water film hole irrigation were examined. Considering the combination of silt content and clay and sand grades, the concept of relative clay content was proved. Based on the concept above, the model involved film hole cumulative infiltration volume, horizontal wetting front movement and vertical wetting front movement was established, and we also found that the model had high precision. Further, the mathematical model of irrigation uniformity analysis under the free infiltration of muddy water film hole irrigation was put forward. The findings provide a theoretical foundation for further study of muddy water film hole irrigation, and technical support for the practical production and application of muddy water film hole irrigation.