Abstract:The structure constant of atmospheric refractive index describes the strength of atmospheric turbulence, and characterizes the random unevenness of the atmospheric refractive severity. Light and radio waves would be affected by atmospheric turbulence propagation in the atmosphere so as to produce a variety of bad effects, such as spot drift, flicker, phase fluctuations and so on. Therefore, the study on the structure constant of atmospheric refractive index has important significance. The conventional radiosonde data was used to conduct simulation research on the structure constant of atmospheric refractive index in microwave band. Results show that in the low altitude, especially in the atmospheric boundary layer, the atmospheric humidity is the main contribution to the structure constant of atmospheric refractive index, while in the high altitude, the main contribution is the atmospheric temperature. In the microwave band, the greatest impact on the structure constant of atmospheric refractive index is not the size of humidity, temperature and pressure,but their gradient, especially the humidity gradient. In the actual low-level measurement of Cn2,the size of humidity and temperature gradient should be mainly considered.