The research was to characterize the no-process manganese element in bleaching process by means of IR, XRD, SEM-EDS. The accumulation of no-process manganese element in eucalyptus cellulose fiber was also studied. The results showed that “fresh” manganese was tabular crystal consisted of Mn3O4, Mn(OH)2 and 7Mn(OH)2?2MnSO4?H2O, while “aged” manganese was grain crystalline consisted of Mn3O4 and MnSO4?H2O. With manganese accumulated in process stream in the range of 0～18.18 μmol/gcellulose, there was a good linear relationship between adsorbed manganese on cellulose and manganese accumulated in process stream. Approximately 40% of “aged” manganese in process stream was adsorbed on cellulose fiber, larger than adsorption capacity of “fresh” manganese, 25%. Adsorption of “aged” manganese in process stream reached the ceiling about 7.66 μmol/gcellulose. The adsorption isotherm of no-process manganese element on eucalyptus cellulose fiber was compatible with adsorption being of the Freundlish type, i.e. a dynamic exchange of particles between the suspension and the fiber surface. 1/n of “aged” manganese was 0.65, less than the “fresh” manganese with 1/n 0.81. ㏒K of “aged” manganese increased significantly compared to “fresh” manganese.