A man who brutally stabbed his ex-partner to death at her south Auckland home late last year will spend at least 17 years behind bars.

Photo: Facebook

Ephraim Joseph Beazley was sentenced today after he pleaded guilty in the High Court in Auckland last month to murdering 34-year-old Xi Wang.

At the High Court this afternoon, Justice Moore described the attack as calculated and heartbreakingly incomprehensible for Ms Wang's family.

Beazley was sentenced to life imprisonment with a minimum non-parole period of 17 years.

Justice Moore considered Beazley's lack of remorse, as well as his early guilty plea and no previous convictions at sentencing.

Police were called to a house in Flat Bush, in South Auckland, on 10 December, where they found Ms Wang unconscious with serious wounds.

She was taken to Middlemore Hospital where she died of her injuries.

Photo: RNZ

Beazley and Ms Wang were in a relationship in Rotorua, which ended poorly about two years before he killed her. They had a son together.

On the night of the murder, Beazley drove from his home in Rotorua to Auckland, where Ms Wang lived.

He arrived about 10pm, parked around the corner from her house, and walked to her door. She answered to find him there with his cap lowered and his head bowed, which would have made it difficult for her to identify him.

Without saying a word he brutally attacked her at her front door with a hunting knife, and stabbed her multiple times all over her body, including her neck.

She was holding their 2-year-old son in her arms the entire time.

From a nearby shopping centre Beazley called police and confessed and told them where he was. He also called a friend and told him too.

Police arrested him shortly afterwards without incident. The knife he used was found in his pocket.

Ms Wang was given first aid by a woman who lived in her house. An ambulance took her to Middlemore Hospital in a critical condition where she underwent emergency surgery, but she later died.