By using the in situ measured data of spectral reflectance and water quality parameters in Aug.22-24, 2009, this study analyzed the spectral characteristics and affecting factors of diffuse attenuation coefficient(K_d) of the Three Gorges Reservoir, and built a retrieving model of K_d(490)at band 490nm.In addition, K_d(490)was inversed by using CCD image of HJ-1 satellite in July 21, 2009.The results showed that the attenuation peaks were not distinct at bands 440nm and 675nm owing to the high content of non-pigment particulates in the water.The dominant affecting factors were absorption of particulates and total scattering water body, while average contributions of the four bands(i.e.440, 550, 613 and 675nm) were 45.48% and 38.21%, respectively;K_d strongly power correlated with the concentration of non-pigment particles between 400 to 700nm.Besides, the average relative error of inversed vs.measured K_d(490) was 17.89% for ground-measured R_ts, whereas the relative error for images data was 28.38%;K_d(490)of the study area was concentrated from 6 to 7m^-1, which accounted for 83.60% of the study area.Additionally, K_d(490)of the tributaries of the reservoir was lower than the main stream, which indicated that the content of particulates in tributaries was relatively low.