In this study, aqueous Cr(+6) ion could be changed by electron beam irradiation(EBI) to Cr(+3)ion and/or insoluble Cr-chemicals. Only EBI required high dosages for changing of Cr(+6). When Na2S2O3 being added into the aqueous Cr(+6), it was easily changed to Cr(+3) and finally to insoluble species, in which maximum yield of Cr(+3) could reach to 100% around at 20-30kGy. High dosages above about 30 kGy suppressed formation of the insoluble Cr-chemicals. Addition of H2O2, strong oxidant, prohibited removal of Cr(+6).