The absolute optical oscillator strength density (OOSD) and generalized oscillator strength densities (GOSDs)below 100eV of N2 are determined with an incident electron energy of 2500eV and an energy resolution of 100 meV.The absolute generalized oscillator strengths (GOSs) for two transitions to the superexcited states at 23 and 31.4eV are determined and their momentum transfer dependence behaviours are discussed.