The valence-shell excitations of nitrous oxide are studied by fast electron energy loss spectroscopy.From the spectra measured at 2.5keV and scattering angles of 3.5°-8.5°,it is found that the asymmetric peak of the transition B 1△ can be well fitted by Haarhoff-Van der Linde function,while the symmetric peaks of the transitions of C1Π and D1∑+ can be well fitted by the Voigt function.The parameters of the peak profiles of B1△,C1Π and D1∑+,i.e.,their energy level positions and linewidths,are determined.With the aid of these parameters,the overlapping spectra measured at the low-energy electron impact can be deconvolved,which provides the possibility to determine the quantitative differential cross sections.The present results also show that the peak profiles of the transitions of B1△,C1Π and D1∑+ are independent of the momentum transfer.