The 24-year-old victim was on the X7 bus travelling from Northampton when it stopped opposite the Harborough Road cemetery, a spokesman said.
"At this point another passenger and a man already waiting at the bus stop pulled the victim off and dragged him into bushes in the cemetery where he was assaulted causing serious injuries to his face.
"The offenders would have had to cross Harborough Road from the northbound bus-stop and enter the cemetery before attacking their victim," he said.
The attack happened between 8.30am and 9am on Thursday April 12. The details have been released today, April 25, by the police.
The first suspect was white, aged 20-21, 5ft 10in with an average build and a black beard. He was wearing a dark blue top and trousers, a high-vis jacket and a black cap with a green logo on it.
The man at the bus-stop was mixed race, aged 25-26, 6ft with an average build. He had a short dark brown beard and was wearing a red baseball cap, a black jacket and black tracksuit bottoms.
Anyone with information about this incident should call Northamptonshire Police on 101 or Crimestoppers, in confidence, on 0800 555111.