Officers are appealing for help to identify him following the discovery of his body at Mount Florida station.
Despite making inquiries, including finger print checks, the man has not been identified and his family have not yet been informed of his death.
The man was seen nearby on 31 December. His body was found on 2 January.
British Transport Police were called to the scene at 11:29 on 2 January after staff found the man’s body. They said the man’s injuries were consistent with him being hit by a train.
The man is described as sallow skinned, slim, with black cropped hair, stubble and a goatee beard.
He was wearing a red baseball cap, black jumper with a silver motif, blue jeans and black boots.
He also had tattoos on both arms, which BTP described as being “of an Egyptian theme”.
British Transport Police urged anyone who recognised the description to get in touch.
Det Insp Brian McAleese said: “The man was last seen on CCTV near to Mount Florida station at approximately 15:50 on 31 December.