Abstract: The He（e,3e） fivefold differential cross-section under the equal-energy share of knocked electron geometry arrangement is calculated, in which the incident energies are 5599 eV and 1099 eV, respectively. The contributions of different interactions as well as their interference effect in the He（e, 3e） process make to fivefold differential cross-section are compared. The result indicates that the theoretical calculation is in agreement with the experimental data in the error range, and each kind of interaction as well as the interference effect to fivefold differential cross-section＇ s influence should be not neglected.

Key words: （e, 3e） reaction, transition matrix element, fivefold differential cross section