Abstract: Firstly, the NJOY nuclear Date Processing System is used to process the fissional nuclides from ENDF/B-VII for sections of fast reactors cross. We use the Matlab software to process the cross section date from NJOY and get multigroup pseudo fission-product for fast reactor transmutation. The fissile parent nuclides are U-235.The cross section data include total cross section, elastic scattering cross section, radioactive capture cross section, the cross section of producing an alpha particle（n, a）, the cross section of producing a proton（n, p）, the cross section of producing one neutron（n, n） and the cross section of producing two neutrons（n, 2n）. The paper uses the neutron energy spectrum to deal with the multigroup cross sections from a fast reactor and validates the multigroup cross section from MCNP and the date form NJOY. It is concluded that the processed cross section date can be used for the accurate calculations of fast reactor transmutation.