Abstract: Based on the data of fog,foggy day’s minimum visibility,hourly visibility and monthly average wind speed,monthly average calm wind frequency,monthly average relative humidity during2016-2020 winter of Urumqi station（south of the city） and Midong station（north of the city）,distribution characteristics and its mainly influence factors of fog in winter in Urumqi city were analyzed and investigated by using statistical method.It shows that,4.6 foggy days of southern city are fewer than54.2 foggy days of northern city during 2016-2020 winter,and foggy days reaches its maximum in January and minimum in November;average minimum visibility in foggy days is 335 m in southern Urumqi and 390 m in northern Urumqi respectively,with the fog generally stronger in the former than that in the latter.The fog of the southern city mainly begins during 17:00-19:00,and dissipates during11:00-05:00;The fog of northern Urumqi mainly begins around 09:00 and during 20:00-22:00,while dissipates during 11:00-14:00;The fog duration are mainly 24 h,accounted for 93.5% and86.3% respectively,while 37.2% and 33.3% for those fogs with duration below within 3 h,with the duration generally longer in northern Urumqi than that in the southern regions;The winter fog in northern Urumqi is more frequent than that in southern Urumqi,with a smaller wind speed,more calm wind frequency,larger relative humidity and special geographical conditions as its dominant causes.