A Sydney man who murdered his wife by setting her bedroom on fire and then pushed her back into the flames when she tried to escape has been jailed for at least 27 years.

Key points: The man was sentenced to a maximum of 36 years in jail

The man was sentenced to a maximum of 36 years in jail The judge found the man lied to the police about trying to save his wife from the fire

The judge found the man lied to the police about trying to save his wife from the fire The wife, prior to her death, had confided with friends about their marital problems

The man, who can only be referred to as AKB, set his wife's bedroom on fire at Guildford in the early hours of October 18, 2016, after she met another man on social media and told her husband she wanted to leave him.

The couple married in Iran in 2005 when the man was 35 and his wife 18, before moving to Australia.

He used petrol to start the fire and then stopped her from trying to escape.

During the man's trial, a neighbour described seeing the woman standing at the window screaming "help me".

Prosecutors called for a life sentence, arguing the crime was in the worst category.

In the NSW Supreme Court Justice today, David Davies sentenced the man to at least 27 years in jail with a maximum sentence of 36 years.

Now 45, he will be eligible for parole in 2043.

During the sentencing, Justice Davies said the couples' relationship had deteriorated and the woman complained to her friends that the man was often angry with her and tried to restrict her freedom, knowing she wanted to leave him.

He said after her death the offender told police and ambulance officers that he tried to save his wife but he could not find her in her room.

"He also denied that he caused the fire. Those were lies," the judge said.

"I am satisfied beyond reasonable doubt that the offender intended to kill the deceased."

"He knew that she could not escape out of the window of the bedroom because there were metal bars on the window.

"He actively prevented her from leaving by the only door from the room."

The judge said the murder was seriously aggravated by having been carried out in the presence of other family members.

"It involves gratuitous cruelty in as much as the deceased was burnt to death while being prevented from escaping from the fire.

"It involved planning and preparation by reason of the introduction of petrol to the bedroom."

The judge noted, however, that he did not impose the maximum penalty for the crime — a life sentence — because it was not a murder committed against a person unknown to the offender.

"I do not mean to suggest thereby that the murder of a spouse or partner is any less serious than the murder of a stranger. However, it is a matter which is relevant to the issue of community protection," the judge said.

He said the man has average prospects of rehabilitation and is unlikely to reoffend.