A Sydney man who was attacked by four intruders armed with a machete and an axe has died, police say.

The 25-year-old died in Liverpool Hospital on Friday night after suffering major blood loss from wounds to much of his body including his wrists, legs and ankles.

He had been in a critical condition since the assault on Thursday, when the men barged into his Lurnea home, in Sydney's southwest, just before midnight.

The man was injured while trying to help his mother, 47, who sustained a wound to the hand when one of the attackers lashed out at her.

He was then slashed with the machete, police say.