The self-developed portable DOAS instrument based on differential optical absorption spectroscopy(DOAS) and composed of optical fiber spectrograph and multiple-pass cell was introduced. The standard gases of SO2 and NO2 were employed to test the accuracy and stability of the system, and then cruise observation of SO2, NO2 and benzene was carried out using the system in Tongling industrial park. During the entire period, the polluted gases showed high concentrations near the contaminated areas and the maximum concentrations of SO2, NO2 and benzene were 5 023.2, 2 195.2 and 162.5 μg·m-3, respectively. With 12.6 m optical path, the detection limits of SO2, NO2 and benzene were 67.0, 169.9, 30.6 μg·m-3, respectively. The portable DOAS system provides a convenient and effective technique for industrial park about emergency and supervisory monitoring and evaluation of gas leakage and fugitive emissions of gaseous pollutants.