The victim, a vulnerable man in his 40s, was attacked in a car park just off Manchester Road in the early hours of Saturday 5 September.
His attacker is described as a white man in his late 20s, of stocky build with short brown hair. He was wearing a white long-sleeved shirt.
Greater Manchester Police have urged any witnesses to contact them.
Det Insp Damian Simpson said: "The victim has understandably been left traumatised by the attack and he continues to be provided with support from specially trained officers.
"If you recognise the man in the images, or if this is you, then please contact the police."
Police investigating the rape of a man in Bolton have released CCTV images of a suspect they are searching for.