The charactistic, the main parameters and the data processing solution of two-wavelength polarization lidar are introduced. The sand pollution transportration process before and after the opening ceremony for the Shanghai World Expo is studied. The results show that the sandstorm was transported from northwest , by backward trajectories analysis the sandstorm comed from the Inner Mongolia region. The sandstorm ceascced and formend again in the sandstorm transportation. After sandstorm, the main wind direction changed into northeast, which was favorable for removing sand particle. The comparision between extinction coefficient by the polarization lidar measurement and the ground PM10 air pollution index (API) is presented ,which shows the satisfactory coherence of the different method-derived results.