Abstract: In order to investigate the influence of various complex test environments on the measurement stability of portable flue gas analyzers for low concentrations of SO₂ and NO, measurement accuracy experiments of SO₂ and NO in 9 kinds of concentrations were carried out. 9 test environments, including high and low temperature, different humidity and external vibration, were designed to test the measurement stability of SO₂ and NO. The factors affecting the measurement stability of the portable flue gas analyzer were analyzed. The results showed that the measurement accuracy of low-concentration SO₂ and NO based on the DOAS portable flue gas analyzer was relatively low, and the relative measurement error was more than ±5%. The measurement accuracy increased with the rise of SO₂ and NO standard gas concentration, which could be reduced to less than ±2%. Both low and high temperature storage environment could significantly-adversely affect the measurement stability of the 75mg/m~3 SO₂, and the absolute errors were 2.84mg/m~3 and 2.64mg/m~3, respectively. Compared with SO₂ measurement, DOAS portable flue gas analyzer could better adapt to complex test environment during NO measurement. The measurement stability of low-concentration SO₂ and NO was relatively inferior in various test environments, and the external vibration environment had the greatest influence on the measurement indication errors, which were 2.8% and 1.3%, respectively. The performance of DOAS portable flue gas analyzer for accurate and stable measurement of low-concentration SO₂ and NO pollutants in complex environment still needs to be further improved.