An intoxicated and speeding driver had already lost his licence when he hit and killed a mother and daughter as they left parent-teacher interviews in suburban Melbourne.

Meili Dai, 44, died instantly and her 14-year-old daughter Xinyu Yuan died shortly after when Thomas Charles Adamson slammed into their car on August 9 last year.

He was jailed in the County Court today for 13 years and must serve a minimum of nine before he's eligible for parole, after pleading guilty to two charges of culpable driving causing death and one of driving while disqualified.

Meili Dai and Xinyu Yuan died in the smash. (9NEWS)

Judge Trevor Wraith said Adamson's actions that day were self-indulgent.

He was angry and had no regard for the safety of others on the road.

Adamson had been drinking and had arguments with his girlfriend and parents immediately preceding the crash.

Experts estimated he was travelling between 155km/h and 165km/h when he braked, just 14 metres from Mrs Dai's car as she and her daughter pulled away from Lighthouse Christian College on the Gippsland Highway at Cranbourne.

The family car was pushed 49 metres, through a wire barrier and into a ditch while Adamson continued for 91 metres down the road.

Judge Trevor Wraith described Adamson's actions as self-indulgent. (9NEWS)

His blood-alcohol level was between 0.120 and 0.165 at the time.

He has a previous drink-driving conviction and was in the middle of a nine-month disqualification from driving.

Adamson was also injured in the crash, suffering a broken neck, pelvis and hips and a mild to moderate brain injury.

Judge Wraith accepted that he showed genuine remorse.

Mrs Dai's husband and son were in court, as well as her parents and brother who travelled from China.

No sentence would heal their immeasurable pain, Judge Wraith told them.

The crash unfolded on August 9, 2017. (9NEWS)

In a statement read during a plea hearing, Zhen Wuan Yuan said he felt helpless since the death of his wife and daughter.

"My spirit has completely collapsed ... nowadays I am alone," he said.

"There is no difference between the night and day for me."

His son Jake said he didn't want to believe his mother and sister had left him forever and that he'd lost the meaning of life since their deaths.

Adamson's family was also in court and hugged him as he was taken away.

He'll be 36 before he's eligible for release.