Abstract:Based on the CALPUFF Modeling System, a regional ambient air quality appraisal system was established for Xi'an. An introduction to the system is given. On the basis of the meteorological data information system and the regional ambient air quality appraisal and forecast system (CALPUFF ) and meteorological data of 2004, the pollution emission inventory and current background status data, and the CALPUFF simulation system, the numerical simulation and analysis are made of the planned construction area status around emission sources, and the characteristics and regularities of pollutants dispersion in five planed construction areas are demonstrated. The differences of urban air pollution influencing factors in different areas are analyzed, and the regional ambient air quality appraisal of the five planed construction areas is quantitatively described.