On the basis of atmospheric aerosol observations collected in Chongqing in winter of 2001—2002,the analysis of physical and chemical characteristics of aerosol,such as number concentration,mass concentration,size distributions,chemical compositions and the relations to meteorological factors were conducted.Results show that the averaged number concentration of aerosol was 225.3 cm^-3 (337.8 cm^-3 in maximum),which was on the same levels of other metropolis in China.The intrusion of cold front and precipitation were the major mechanism for aerosol cleaning out and the fog occurrence had great influence on the general diurnal variations pattern of aerosol.The PM₁₀ accounts for 60% to 80% of TSP（Total Suspended Particles） in mass concentration.The elements of aerosol originating from anthropogenic source,such as S,Zn,As and Pb,were enriched in fine aerosol particles.