Abstract: Abstract： As one of the three largest natural rights, the right of life contains not only the life safeguard and justice protection but also the life interest control. The mercy killing belongs to the right of life, including two aspects: choosing the death time and the death condition. While the right of the mercy killing only applies to the proper people, the action for choosing the mercy killing is a right instead of an obligation.

Key words: right of life interest control, right of mercy killing, subject of civil right, Key words： right of life