Abstract: Atmospheric aerosol particles were measured at Jinghong(Yunnan Province) and Zetang(Tibet Region) meteorological observatories in the winter 1997/1998,and their physicochemical properties,such as mass concentration,sizedistr ibution,optical absorption coefficient and chemical composition,were analyzed.Results show that aerosol particles at the two sites have significant physical and chemical difference and also different from the results at other locations.Zetang has a low number density with arelative high mass concentration.This study has great practical importance to add to ourknow ledge of Chinese aerosol distribution and their effectson the regional climate.