Abstract: The characteristics and their causes of air quality in Shanghai during the Spring Festival in 2016 were analyzed and compared with the air quality during the same period in 2014 and 2015.The results show that the air quality in most days during the Spring Festival in 2016 is good,but light pollution with the three level of air pollution occur on the New Year Eve due to the burning of fireworks and the unfavorable synoptic condition.Based on the meteorological condition,back trajectory analysis,and pollution distribution in China,it is concluded that the unfavorable atmospheric dispersion conditions on the New Year Eve in 2016 helps the accumulation of pollutants in the local area.In addition,the transport of pollutants from upstream area is also the major cause of air pollution in Shanghai.The variation of hourly PM_2.5 concentration within and outside the ban region of fireworks and their absolute difference values demonstrate that the fireworks forbidden control the pollutant emissions at a certain degree.In a comparison of PM_2.5 concentration during Chinese New Year period from 2014 to 2016,PM_2.5 pollution in 2016 is significantly less than that in 2014 and has lower PM_2.5 peak concentration and shorter pollution duration than 2015.The reduction of emission sources due to the close of works and decrease of motor vehicles on road during the Spring Festival period has a positive impact on air quality.