A mobile differential absorption lidar (DIAL) system for atmospheric pollution measurements has been developed. It is the first mobile system for air pollution monitoring in China. This lidar system allows three-dimensional measurements by using a steering unit, and can measure four kinds of pollutants in atmosphereaerosol, SO2, NO2, and O3. The lower detection limit of the SO2, NO2, O3, and aerosol's extinction coefficient is 0.01 mg/m3,0.04 mg/m3, 0.01 mg/m3, and 10-4 km-1 respectively. The best spatial resolution and maximum measurement range are 7.5 m and about 3～10 km respectively. Using this system, range-resolved measurements with high sensitivity over large areas can be made. The lidar system in some detail and its performance are described.