Abstract: Based on the Observational data of fog from 142 base stations of Sichuan in 51 years,used simple linear regression,the basic climatic characteristics of fog in our province in temporal and spatial distribution are analyzed.The flowing phenomena were found:1.Distribution of fog showed obviously regional geographical features,which showed that fog days in plateau were fewer than in basin.There are barely fog days all the year round in most regions of plateau (average < 1 d).Average fog days in basin and mountainous terrain were up to 37 d.Emei Mountain was fogged all the year round (average up to 311.8 d).2.Seasonal change of fog was also connected with surface geographic feature.The maximum of fog in basin and mountainous terrain was winter,differently in plateau which was autumn.3.Fog days in Sichuan has obvious interdecadal variation characteristics,which experienced less-more-less process,and increased over time.4.Change of fog in Sichuan also has close connection with surface geographic feature.Change in plateau was negative,but positive in basin and mountainous regions.