The noise propagation distance of cross airspace aircraft is extremely far， and the impact of the atmosphere cannot be ignored. When the conventional civil aircraft conducts the actual flight test of noise airworthiness， the test reference atmospheric conditions are specified in the CCAR36. However， under the influence of complex factors such as non-uniform temperature and humidity， wind speed and wind direction， the actual measurement environment often deviates from the reference conditions. Although the regulations allow simplified compensation by introducing sound absorption coefficient correction， the extent of its correction needs to be further evaluated. In order to solve the problems above， a far-field sound propagation model that can consider the influence of non-uniform atmospheric was developed based on the ray-tracing method， the specific influence of the non-uniform atmosphere on the noise measurement was explored， and compared the difference between the sound attenuation correction method suggested by the CCAR36 and the result of ray-tracing model， the correction results of the quantitative influence of the ray-tracing model on the non-uniform atmosphere are closer to the reference atmospheric conditions defined by the regulations， showing the superiority of the method in terms of accuracy. The results can provide an effective scheme for accurately evaluating the far field sound propagation of cross-airspace aircraft and conventional aircraft under real atmospheric conditions， as well as a reliable tool for analyzing the impact of aircraft noise on airport communities and refining noise data in airworthiness flight tests.