Abstract:Based on the Meticulous observational data of hourly haze, visibility and air quality monitoring of Shenzhen during 2010~2013, Seasonal variations of haze, the relationships of the meteorological conditions and air quality to haze were analyzed in order to provide the basis for issuing haze warning and forecast more pointedly. The results suggested that the annual haze days of Shenzhen presented an increasing trend overall and the phase change of a down trend since 2009. The monthly variations of haze days showed "V" type, which implied the haze occurred mainly in autumn and winter rather than in spring and summer. There were more long duration and serious haze processes in autumn and winter but short duration ones in spring and summer. The haze was often accompanied by mainly mild air pollution (35%). PM2.5 was the primary pollutant followed by O3, which indicated that PM2.5 was the main cause of haze weather and photochemical pollution was also serious in Shenzhen. There was significant variation of PM2.5, PM10 and O3 with the seasons. The primary pollutants changed with the seasons that PM2.5 was the main pollutant (above75%) in winter and spring, but O3 and PM2.5 were in summer and autumn. The wind and relative humidity were the important influencing factors of haze. The 80% of moderate and severe haze occurred under the wind speed <2m/s and relative humidity 70%~90% ,which suggested the weaker wind speed and the greater humidity were conductive to the emergence and development of haze.