Atmospheric stellar occultation technology can detect information about the density of various trace components and atmospheric temperature and so on in the planetary atmosphere. The above parameters were obtained by using the atmospheric transmittance. An occultation model was established based on the principle of stellar occultation. The spectral absorption characteristics of gas molecules were analyzed, and then transmittance of various atmospheric components were obtained through simulating how it worked by model. The atmospheric component density was obtained by inversion of atmospheric transmittance and this model was verified through the comparison of MSISE-00. The results of the two were in good agreement. Furthermore, the signal-to-noise ratio and relative error of the spectrum were estimated, and signal-to-noise ratio and relative error about different stars were discussed, and then the range of magnitude of the target stars was given. The preliminary results show that the target stars in the range of -1.45-3.55 is used as the light source for detection, the signal-to-noise ratio is above 100, and the relative error of measurement is as low as 1%. The results of this paper provide preliminary theoretical guidance for the development of stellar occultation detection in the near-space of the Earth and other planetary.