Fractal features of micro aggregate and available nutrients in Chao soil were studied by mixing organic materials (bean stalk, corn stalk, chicken manure and pig manure) into the soil samples on low-yield fields in Henan Province. The results indicated that: 1) The mass fraction of 0.1 -0.053 mm soil particles was 7% -13% higher than the CK treatment with the increase of added organic materials, and reached the level of significant difference; correspondingly the mass fraction of soil particles less than 0.053 mm size was lower than the CK treatment. 2) Fractal dimension of soil particles ranged between 2.52 and 2.72 by the fractal model, and it had a very significantly negative correlation with the mass fraction of soil particles with 0.1 - 0.053 mm size (R = - 0.945) and a very significantly positive correlation with soil particles with the size less than 0.053 mm (R = 0.981). Distribution of micro aggregates was changed with the transition from the single application to the mixed treatment of stalk and manure, and the fractal dimension decreased. 3) Compared with the CK treatment, the mass fractions of the available nutrients in the different particle sizes and in the soil itself were significantly increased with the addition of organic materials. The mass fractions of available nitrogen, potassium and phosphorus increased by 168% - 528%, 141% - 1000% and 16% - 81% compared with the CK treatment in 0.1 -0.053 mm size soil particles, and 13.4% -44%, 17% -170% and 21% -66% compared with the CK treatment in soil particles less than 0.053 mm, respectively. The mass fractions of available nitrogen was in the order as the application of stalk (73.1 mg/ kg) > application of double mixture of stalk and manure (69.3 mg/ kg) > application of mixture of stalk and manure, application of pig manure(63.0 mg/ kg) > application of chicken manure (59 mg/ kg) > the CK treatment (49.9 mg/ kg), and that of available potassium was in the order of the application of the bean stalk (140 mg/ kg) > application of double mixture of stalk and manure, and corn stalk (120 mg/ kg) > application of mixture of stalk and manure (86.5 mg/ kg) > application of manure (76.8 mg/ kg ) > the CK treatment (56.5 mg/ kg), that of available phosphorus in the order of application of corn stalk (40.9 mg/ kg) > application of manure and application of mixture of stalk and manure (35.91 mg/ kg) > application of bean stalk (30 mg/ kg) > the CK treatment (26.8 mg/ kg ), and that of total soil nutrients was in the order of bean 32 treatment and corn 32 treatment(259 mg/ kg) > application of double mixture of stalk and manure and bean16 treatment (225 mg/ kg) > corn 16 treatment (210 mg/ kg) > application of mixture of stalk and manure and pig manure 8 treatment (191 mg/ kg) > chicken manure treatment (191 mg/ kg) > pig manure 4 treatment (161 mg/ kg) > the CK treatment (133 mg/ kg ). In brief, both the mass fractions of the nutrient of different sizes and the soil itself were increased by adding organic materials into sandy soil.