A "sadistic" Melbourne man who raped his ex-girlfriend twice while burning her with a cigarette, had only just been released from jail for brutally assaulting her.

The 51-year-old man, who cannot be named for legal reasons, raped his former partner in a "brazen and pitiless" act of revenge in June 2015, calling her a dog for going to the police.

He'd been out of jail only three weeks after dragging the woman - 20 years his junior - for five metres by the hair from a moving car the previous year.

She was only saved from the ordeal when a chunk of her hair came out.

After spending nine months in jail, the man visited the woman, using rolled-up police documents to hit her.

After raping her and burning her around her genitals, the man laughed and "seemed very happy with himself", the victim said.

But as he was sentenced to 21 years in jail on Thursday, the County Court of Victoria was told it wasn't the first time he had raped a woman.

In 1996, the man and his friend met a 29-year-old woman seeking accommodation.

The pair said they'd help her but after enticing her into their vehicle, they dragged her to the side of a highway and repeatedly raped her.

In November a jury found the man guilty of common assault, making a threat to kill, two counts of rape and intentionally causing injury after the 2015 rape of his ex-girlfriend.

"You intended to punish (the woman) and thought you could get away with it by threatening to kill her, " the sentencing judge said on Thursday.

"Your conduct was sadistic and merciless.

"Your cowardly acts were both brazen and pitiless."

The woman had previously told the court she suffers panic attacks, flashbacks, anxiety, dizziness, insomnia, is unable to work and experiences constant feelings of terror and doom.

"These images haunt my days, my nights, my dreams and my existence," she said in a statement.

"Now I am a shell of my former self."

The judge said the man showed no remorse, had poor prospects for rehabilitation, and did "not respect the rights of women to refuse your sexual advances".

"You have raped a stranger, you have raped a person you claimed to have loved," the judge said.

"You pose a very real danger to the community."

As he was sentenced, the man swore at the judge and ripped up documents he was meant to sign after being registered as a serious sex offender.

He will be eligible for parole in 17 years, and has already spent 932 days in detention.