Based on finger print absorption, the technique of passive differential optical absorption spectroscopy (DOAS) enables the qualitative and quantitative measurement of a variety of pollutants found in the atmosphere using scattering light as light source. As a new type of photoelectric detection technology, imaging detection technology can get the spatial and spectral information of the detection area at the same time, which makes it possible to realize two-dimensional imaging measurement of the pollutants when combined with passive DOAS. The experimental system consisted of convex grating Offner imaging spectrometer, matrix CCD, UV lens and scan table is introduced, and the optical design of the Offner imaging spectrometer is described in detail. The software system based on MFC was developed, which realized such functions as: detector parameter setting, data acquisition and display, data storage, the control of scan table, imaging of the target, and the combination of image with spectrum. The system was carried to scan the plume from a fossil power plant in a field measurement. And the column density of SO2 was retrieved from processing of the scattered sun light spectra collected by the system by means of the spectral analysis method of passive DOAS. The results show that the system can run stably and be used to realize two-dimension imaging measurement of the pollutants.