In view of two-dimensional distribution reconstruction of the atmospheric trace gas concentration, a new method, passive Differential Optical Absorption Spectroscopy (DOAS) tomography for atmospheric trace gas distribution reconstruction, is put forward. Two MAX–DOAS is applied to scan SO2 plume, the DOAS technique is used to inverse gas column concentration, and algebra iterative algorithm (ART) is applied to extract information of the concentration distribution. Moreover, the Gaussian plume is adopted as reconstruction object, and the method of numerical simulation is adopted to study and analyze reconstruction effect. The analysis shows that the reconstruction result is consistent basically with the model, so the method of gas distribution measurement is feasible. In order to study influence of error in the actual measurement on reconstruction results, the different random error is added to projection data. The study shows that a reconstruction result is insensitive to random error in projection data.