Abstract: Soil structure and pore distribution will be changed by rock fragment, which affects the air permeability and water conductivity. The inherent mechanism of soil air permeability by single rock fragment particle size in stony-soil medium was discussed, which was the basis for investigating the soil air permeability in complex stony-soil medium. Influences of soil air permeability in stony soil medium in different samples?which soil?particle?size?less?than?2mm (sand, sandy loam soil, clay loam soil), different rock fragment contents (10%, 20%, 30%, 40%) and different rock fragment particle sizes (2-3, >3-5 mm) were analyzed. Results showed that the values of samples?with particle?size?less?than?2mm were in the order of sand >sand loam soil > clay loam soil. For the stony soil medium with the same rock fragment content, the values of soil air permeability were in the order of sand loam soil > sand > clay loam soil. The presence of rock fragment improved soil structure and the performance of soil air permeability, made the permeability of stony-soil Medium better than that of clay loam, decreased the air permeability of sand loam soil and sand. And depression amplitude of sandy soil was far larger than that of sandy loam. Soil air permeability of rock fragment particle of >3-5 mm was greater than that of 2-3 mm when the rock fragment content in sand loam soil was less than 30%, and the situation was opposite when the rock fragment content in sand loam soil was 40%; air permeability of stony soil medium was little difference under the two rock fragment particle sizes condition.