Abstract: Based on the daily air pollution monitoring data of 120 environmental protection key cities in China as well as surface meteorological data and sounding data from June of 2000 to August of 2013,the characteristics of air quality situation in typical representative cities of China and its relationship with meteorological parameters were analyzed.The results show that the spatial distribution of API (Air Pollution Index) in China has a trend of reducing from the north to the south.The seasonal distribution of API in northern cities presents a pattern of "winter high and summer low",and the amplitude of API variation in northern cities is significantly greater than that in southern cities.The temperature inversion layer thickness in northern cities is basically higher than that in southern cities,and temperature inversion layer thickness in representative cities shows a "U" pattern on an annual scale and has characteristics of strong in the winter half year and weak in the summer half year.The maximum mixing layer thickness and inversion layer thickness change in an inverse phase.The maximum thickness of mixing layer and its amplitude in high-altitude cities in the northern and southern regions are large,while those in low-altitude cities in the southern region are small.Meteorology parameters of air pollution have a close relation with API.Heavy pollution in northern cities during winter results from both of the increase of the pollutant emission due to heating and the reduction of diffusion capacity in the atmospheric boundary layer that can be reflected by the pollution meteorological parameters.It could provide a reference for the potential prediction of air pollution.

Key words: Air Pollution Index (API), Air quality, Maximum mixing layer thickness, Inversion temperature, Meteorological parameter