Field work was carried out in Guanting Reservoir on September 5,2012 to study the absorption characteristics of total particulates,phytoplankton pigment,tripton and chromophoric dissolved organic matter (CDOM).The results show that: (1) In autumn,phytoplankton pigment absorption plays a major role in total particulates absorption,thus the absorption of total particulates has the similar characteristics as that of phytoplankton pigment.(2) The absorption coefficients of CDOM and tripton decreased exponentially with wavelength increasing.The slope coefficient of tripton absorption spectral Sd is much smaller than that of other eutrophic waters (eg.Lake Taihu,Lake Dianchi,Lake Chaohu).The slope coefficient of CDOM absorption spectral S_g is similar to Lake Taihu and Lake Chaohu.(3) Significant linear relationship was found between a_ph (440),a_ph (676) and C_Chl.a , but the specific absorption of phytoplankton (a_ph^*) at 440 nm and 675 nm keeps a stable level and has no obvious relationship with C_Chl.a.(4) Significant linear relationship was also found between a_d (440),a_d (676) and C_Chl.a ,which indicates tripton in autumn Guanting Reservoir mainly comes from the degra_dation of phytoplankton.(5) Absorption coefficients of different components from different sites of Guanting Reservoir show four different types of contributions to the total absorption coefficients.In more eutrophic area (Gui Area),phytoplankton dominates water's light absorption,while in less eutrophic area (Zhong Area),particles and CDOM play the same important roles in light absorption.