Abstract: In this paper,the pollution characteristics,circulation situation and meteorological conditions of different growth types of PM_2.5on heavy pollution days were analyzed in winter in Urumqi during 2015-2021 based on hourly ground-based conventional observations,air quality data and combined with ERA5 reanalysis data.The results show that,the proportion of heavy PM_2.5 pollution decreases from 41.2% to 8.6%,and the number of heavy PM_2.5pollution days decreases from 63 days to 13 days in winter in Urumqi during 2015-2021.Besides,more than 70%of heavy pollution days with PM_2.5 concentration growth distribute within 60μg/m~3.According to the identification method of different growth types,PM_2.5 heavy pollution in Urumqi are mostly slow growth type in winter during2015-2021.By comparing and analyzing explosive growth type and slow growth type of circulation situations,both types are mainly influenced by northwesterly or westerly air currents in the 500 hPa high altitude over the Eurasian.The high pressure ridge of the explosive growth type is stronger,and Urumqi is located behind the high pressure centre and has a larger pressure gradient.While the high pressure ridge of the slow growth type is flatter,and Urumqi is under the control of the mean pressure field behind the high pressure,and the pressure gradient is relatively small.By comparing the thickness and intensity of the inverse temperature in the boundary layer of the two types,it is found that the thickness of the average inverse temperature layer of the explosive growth type is significantly larger than that of the slow growth type between 925-700 h Pa,and the intensity of the inverse temperature of the former reaches 1.8℃·（100 m）^-1,which is significantly higher than that of the slow growth type(1.2℃·（100 m）^-1),thus it can be seen that the main factor causing the two types is due to the vertical characteristic distribution structure of the inverse temperature in the boundary layer.