The outer valence electron momentum distributions of benzene are reinvestigated with theoretical calculations in-volving the vibrational effects. The results are compared with recent experimental measurements [Phys. Rev. A 98042705 (2018)]. The significant discrepancies between theories and experiments in previous works have now been interpreted quan-titatively, indicating that the vibrational motion in benzene molecule has noticeable infl uence on its electron momentum distributions.