A differential absorption lidar (DIAL) system has been developed for background atmospheric SO2 and NO2 measurements. Second harmonic and third harmonic (532 nm/355 nm) of two Nd∶YAG lasers are used to pump four dye lasers, respectively. Two pairs of laser beams 300.05 nm/301.5 nm and 446.6 nm/448.1 nm are obtained for profiling atmospheric SO2 and NO2. Observation results show that accuracies of atmospheric SO2 and NO2 measurements under clear weather condition can be within ±2.0×10-9 and ±5.0×10-9, respectively, when spatial resolution is set to 15 m and integration time is seted to 30 minutes. Averaged atmospheric SO2 and NO2 concentrations observed through SO2/NO2 DIAL conform with the results of meteorological department at the same time. It shows that DIAL technique has the ability to measure the space-time distribution of low concentration of SO2 and NO2.