The death curse he used backfired and he died at the age of 71.

In the last few novels, Voldemort's Horcruxes were successively destroyed, and when Voldemort attacked Harry Potter with the Death Curse on the edge of the Forbidden Forest, he destroyed the artifacts that Voldemort had accidentally left in Harry's body. The spirit was separated, but Harry himself escaped. In the end, Voldemort and Harry dueled with wands, during which Neville Longbottom killed Nagini, the serpent who was Voldemort's last Horcrux.

At this time, Voldemort attacked Harry again with the Death Curse. Since this attack was really fatal, the Elder Wand in Voldemort's hand reflected the attack because it could not harm its real master, Harry Potter. Voldemort, who lost all his Horcruxes, was killed by his own death curse.

Extended information:

Avada Kedavra——

Avada Kedavra is mentioned in the fantasy novel "Harry Potter" A curse that first appeared in "Harry Potter and the Chamber of Secrets" and is one of the three Unforgivable Curses. The Unforgivable Curses include Avada's Kedavra, Cruciatus Curse, and Imperius Curse. It was once one of Voldemort's favorite magics.

2. Effect

After the spell is cast, a dazzling green light will be emitted, and the person hit by the spell will die immediately, usually without leaving any trace. Only one person in history has survived, and that is Harry Potter. He was the first person to escape from the wand of Lord Voldemort (Tom Riddle). (Including Professor Albus Dumbledore also died under the killing curse of Professor Severus Snape, and Voldemort was not spared in the end.)

3. Special method: The Elder Wand

If a person who is not the Elder Wand's owner uses the Elder Wand to cast the Killing Curse on the Elder Wand's owner, the spell will have no effect and will rebound. This is how Voldemort died.