A method for measuring the two-dimensional distribution of air pollutants from power plant-imaging differential optical absorption spectroscopy (IDOAS) technique is introduced. It is based on an imaging spectrometer combining with a rotating platform, which can realize two-dimensional scanning and hyperspectral measurement of the target area. The spectrum is calculated using the differential optical absorption spectroscopy (DOAS) algorithm to get two-dimensional distribution of pollutant gas in the area. Then the diffusion trend of pollutant can be further analyzed. The ground-based IDOAS system and its principle are introduced, and a field experiment is performed. During the field experiment, the two-dimensional distribution of SO2 from power plant smoke plume is acquired, realizing the visualization of power plant emissions. The SO2 emission rate and average concentration estimation method is analyzed combining with wind speed. The power plant SO2 emission rate and average concentration is evaluated respectively as 210 kg/h and 6.7 mg/m3.