The radiation characteristics of the atmospheric boundary observed in limb view is significant in many fields, such as target recognition, infrared warning and weather forecasts and other fields. Different atmospheric conditions, observation geometry and spectral range will affect the radiation characteristics of the limb atmosphere. The specific parameters are different, and the degree of influence is also different. A hemispherical accumulation method (HLA) was proposed to calculate the background radiation of the limb detection. Based on the characteristics of the limb detection, the sensitivity of the mid-and far-infrared two-band fronts detection to atmospheric mode parameters and gas content parameters is studied. Using the HLA model, the sensitivity analysis of the radiation characteristics of the marginal atmosphere was carried out, and the quantitative calculation results are given.