Abstract: Utilizing the hourly visibility data of the past 10 years of Baiyun International Airport, a statistical analysis on the climate characteristics of low visibility and a research on the weather phenomenon and systems causing low visibility has been made in this paper. The results have been obtained as follows: There are conspicuous monthly and daily variations for the low visibility of Baiyun International Airport. The mean times of low visibility are obviously in inverse ratio to the durations of low visibility. The weather phenomenon of low visibility obstruction is fog and rain. In winter, the main system causing the severe visibility is weak ridge, and less severe visibility occurs in the cold sector of front.