差分光学吸收光谱法(DOAS)应用于固定污染源烟气排放监测时，烟气中污染气体SO₂浓度较高将产生非线性吸收问题。提出了一种非线性补偿方法，即将实际浓度所对应的气体分压与反演结果所对应的气体分压之比与反演结果之间的对应关系拟合成补偿函数，利用此补偿函数对反演结果进行非线性补偿。实验结果表明：该补偿方法能较好地减低高浓度气体非线性吸收产生的影响，可提高气体浓度反演精度。

Nonlinear absorption occurs when the differential optical absorption spectroscopy (DOAS) is used to monitor the flue gas with high SO₂ concentration from fixed pollution source.A nonlinear compensation method is put forward,in which the ratio of the pressure component of the actual concentration to the pressure component of the inverted result versus the inversed result is fitted into a compensation function. The compensation function is used to compensate the inverted result nonlinearly. Experimental results show that the effect caused by the nonlinear absorption of high-concentration gas can be reduced with the proposed method and it can improve the inversion accuracy of gas concentration.