The victim was grabbed by his clothes, beaten up and robbed of a quantity of cash as well as his smart phone on the 7.55pm service on Thursday 4th August.
CCTV images of two men they would like to speak to in connection with the incident have been released.
Detective Constable Ian Grice of British Transport Police said the young man, from Worksop, was approached by two other men who boarded the train at Shirebrook.
“This was a violent, aggressive and targeted attack on a man travelling alone,” he said.
“The pair violently assaulted the victim, grabbed him by his clothes, and pinned him to one of the tables where he was threatened and ordered to hand over his smart phone.”
“They also took a small amount of money which he was carrying at the time.”
The two men wanted by police then got off at Worksop station and were seen to leave the area via Turner Road.
Anyone with any information, or who recognises the men pictured, is asked to contact British Transport Police on 0800 40 50 40 or call Crimestoppers anonymously on 0800 555 111.