Aerosol optical depths(AOD) were retrieved by using the vapor pressure and visibility data over 70 stations in China from 1999 to 2003,then its statistical characteristics were analyzed.It is found there Sichuan Basin was the maximum area of yearly mean AOD,and another two large value centers were in the middle and lower reaches of Yangtze River and the coastal area of Guangdong,but AOD was lower in the Northeast China and Northwest China and Yunnan.The distribution of AODs for each month was similar,but differences were also obvious.During 1999-2003,the national average AOD showed a weakly increasing.The monthly average AOD had a close negative correlation with visibility.