In order to explore the influence of sediment on soil structure under the condition of muddy water irrigation，four typical sediment particle gradations (which were quantified by the physical clay content with a particle size of less than 0.01 mm，d0.01:9.87%，20.48%，28.68%，37.39%) and two sand content rates (3% and 12%) were set up through the lab test of free infiltration of muddy water film hole irrigation.There were eight treatments in the experiment.The effects of muddy water characteristics on soil particle composition and fractal characteristics of film hole irrigation were studied.The result showed that the characteristics of muddy water had a greater impact on the soil particle composition of film hole irrigation.The relative content of fine particles in the deposition layer soil was lower than that of sediment in muddy water，which increased with the increase of sand content rate and d0.01 of muddy water.The soil particle composition of the stranded layer was opposite to that of the deposition layer，that is，the relative content of fine particles was higher than that of the original soil，which also increased with the increase of sand content rate and d0.01 of muddy water.The interaction of sand content rate and d0.01 of muddy water also had significant effects on the soil clay content and sand content at each depth of the stranded layer.The fractal dimension of soil particles in the stranded layer was greater than that of the original soil，and the difference between them was the largest in the layer of 0～2 cm.With the increase of infiltration depth，the increase of soil fractal dimension was less.At the same soil depth，the fractal dimension increased with the increase of sand content rate and d0.01 of muddy water.