Abstract: The author in this article focus on analyzing the cause of the smog phenomenon under the influenced visibility of weather in winter in Manchuly area ,fulfilling the analysis based on the counts of smog appearance in 1657-2009,and find out the law of the monthly and yearly changes in smog winter.The smog days of manehuly mainly concentrated in November and February next year according to the statistics.after analyzing the smog data in recent 10 years in detail and linking it with the feature of weather when smog took place,we finally find out the focus point of meteorological forecast under the smog phenomenon,concluding that the smog days almost appear under the control of the high pressure system,the main reason for the smog mostly appeared in winter is that there are more of emission of smoke and dust than that in other seasons ,in winter the speed of wind is lower and the atmosphere structure is stable.