Abstract: Water transparency is an important parameter to describe the optical properties of water body and an evaluation index of marine environmental quality. In this study, a three-band ratio model was employed and applied to MODIS remote sensing reflectance data, the water clarity in the Yellow Sea from 2003 to 2020 was estimated. The results show that the transparency gradually increases from the near shore to the open sea, with low value in the western part of the Yellow Sea and high value in the middle part of the South Yellow Sea. In terms of time, the transparency shows a declining trend. Empirical orthogonal function analysis shows that the first mode has the strongest correlation with the concentration of chlorophyll a and a high correlation coefficient with the concentration of suspended matter, indicating that the change of seawater transparency is mainly affected by the optical components of water. The second and third modes show that sea surface temperature and sea surface salinity are the main covariables causing the change of transparency. Long-term monitoring of water transparency is an important part of water quality monitoring and marine ecosystem protection.