The Taihu Lake is selected the study area. By collecting water surface spectral data of analytical spectral devices (ASD) by the ship, atmospheric data of CE318 sunphotometer on the shore, and the moderate resolution imaging spectroradiometer (MODIS) image data on the same day, the data were used to get optical properties of atmosphere in the study area. A method based on measurements for determining the aerosol type is presented. By using the nearly synchronous measurements of the data from surface spectrum and the sunphotometer with the image, using the radiative transfer model 6S (second simulation of a satellite signal in the solar spectrum), and varying the components of the aerosol type, a look-up table (LUT) is made for the radiance on the satellite. When the total relative error of the defined parameter for relative error gets to the least, the aerosol type is decided. It has been used to get the optical characteristics including polarized phase function of the poly-disperse aerosols by the improved Mie code. The aerosol type is used to retrieve the aerosol optical depth (AOD) in Taihu Lake area, and its retrival accuracy has been improved a lot compared to the measured value from CE318. The method and results will be provided for the supporting of the remote sensing applications, such as the atmospheric optical properties, the radiative transfer calculation, the retrieval of AOD, and the atmospheric correction.