The in-situ data of sky radiometer observed on ship at East China Sea during five cruises from April 2006 to November 2007 are used to validate the corresponding 869 nm aerosol optical depth data included in MODIS standard ocean color products. The spatial box of 10 km×10 km and temporal interval of ±1 h are used as the matching criterion. The results show that: 72% of the match-up data fall close to, or within the expected error range of Δτ＝±0.03±0.05τ. As there are some differences in the precision of MODIS-derived aerosol optical depth according to regions and seasons, data consistency over the East China Sea is better than the Yellow Sea, while the consistency in the winter of 2006 is better than the fall of 2007. In the fall of 2007, MODIS retrieval values are systematically overestimated. The reason for this phenomenon was analyzed. It seems that twelve pre-calculated aerosol models used by MODIS retrieval algorithms can′t match the optical properties of the actual aerosol very well, and further analysis with all of match-up data confirmed the conclusion.