Police received reports that five men were assaulted by an unknown man on a train trip between Parramatta and Auburn train station at 11.15pm on August 8.
The five men in their 20s were not seriously hurt.
Investigators released a public appeal for information to try and identify the offender.
Following investigations, a 28-year-old man was arrested at Auburn Police Station at midday yesterday.
The man from Strathfield was charged with affray and was granted conditional bail.
He will appear in Burwood Local Court on August 28.
