It comes after a man is believed to have sat down next to another passenger on the train at around 8.10pm on April 19 and pulled out a knife, before making demands for his property.
The victim was able to escape by pushing the man away, then leaving the train at the next stop.
Police have released the images of someone they wish to speak to in connection with the incident.
It has also asked for anyone with any information to contact them by texting 61016 or calling 0800 40 50 40.
A spokesman for British Transport Police said: "Do you recognise this man?
"Detectives investigating an attempted robbery at Walsall are today releasing these image in connection.
"At around 8.10pm on April 19, a man boarded the same train as the victim and sat next to him.
"He pulled out a knife and made demands for his property, threatening the victim with the knife.
"The victim managed to push the man away and he left the train at the next stop.
"Officers believe the man in the images may have information which could help their investigation.
"If you recognise him, or have any information, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 616 of 19/04/2023
"Alternatively, you can call Crimestoppers anonymously on 0800 555 111."