A 70-year-old Perth father of six who attempted to kill his meth-addicted son by repeatedly striking him to the head with a claw hammer has been jailed for five and a half years.

Ronald James McDonald attacked his 23-year-old son as he slept on his mother's couch in their Dianella home on August 15 last year.

The Supreme Court was today told McDonald had been at the home trying to help his estranged wife after their son, who had an ongoing drug problem and was abusive towards his mother in the months prior, began "screaming and threatening to smash things".

After pacing around the patio thinking about what to do, McDonald took hold of a claw hammer and began striking his son to the head.

The first blow woke the 23-year-old and McDonald held him by the jumper to prevent him from escaping.

He then struck him a further three or four times, fracturing his skull.

After his son broke free McDonald called triple-0 and immediately admitted to police he attempted to kill him because he believed it was the only option available to his family.

Justice Katrina Banks-Smith said sentencing McDonald was a difficult exercise and that his lawyers had eloquently described "the other side of the methamphetamine equation".

"You thought you could no longer cope with your son's behaviour," she said.

"There is room for significant sympathy and empathy for your position but violence is no answer."

The court was told McDonald was described by his ex-wife as a "godsend" and in a reference letter addressed to the court as a "peacemaker" who found himself in his "predicament" out of frustration.

Justice Banks-Smith found McDonald suffered from depression which deprived him from being able to make calm and rational decisions on the night of the offence.

She said McDonald's family, who were present in court today, remained supportive of him.

The victim objected to a life-long violence restraining order being imposed, a request accepted by Justice Banks-Smith.

Justice Banks-Smith said she took into account McDonald's mental illness, his prior good character, his guilty plea and his deep remorse in her sentencing.

But she said while the offending was on the "lower end" of the scale compared to other offences of its kind, it was too serious to warrant a suspended sentence.

McDonald was made eligible for parole and his sentence was backdated to February 22 this year.

His family, including the victim, appeared visibly distressed after the court hearing and did not comment outside court.