Abstract: Atmospheric particulate matter (PM2.5 and PM10) were the primary pollutants that affect urban air quality.Atmospheric particulate pollution resulted from weather conditions was serious in autumn and winter thes years.In this paper,analysis was made of the daily variation of atmospheric particulate matter concentration in the autumn and winter of Chengdu in 2016 and the daily variation of atmospheric particulate matter concentration in urban forest.The results showed that (1) atmospheric particulate matter concentration and meteorological conditions had a significant correlation,favorable weather conditions could accelerate the proliferation of atmospheric particulate matter,and effectively improve the air quality.(2) The diurnal variation of PM10 and TSP in urban forest was lower than that in forest,and the diurnal variation of atmospheric particulate matter in urban forest showed the pattern of "morning and evening high and low daytime".