The characteristics of aerosol optical depth (AOD) and Ångström exponent as well as the relationship between the AOD and particulate matter (PM10), were measured and analyzed at the Chengdu station over the Sichuan Basin in China from February 2007 to December 2009. High monthly AODs were observed in March, August and December, while a low value was observed in October. Monthly variations in Ångström exponent were opposite to the AODs in March and August. The averaged PM10 showed a significantly seasonal variation with a peak in winter. There is a complicated (not linear) positive correlation between total AOD and PM10 near the surface. Three typical cases under the conditions of dust and haze were studied, and the results showed that the AODs on the dust days were largest while minimum AODs occurred on haze days. On the contrast, the Ångström exponent distributions among three weather conditions were opposite to the AODs. The 3-day back-trajectory analysis indicated that the origin of the air masses largely affected the aerosol optical properties over the Sichuan Basin.