Scientific Technology has been ever eliminating many natural disasters. It predicts the tract of typhoon, prevents from flood, controls famine, conquers plague, and lengthens the average life span. Scientific technology reduced the natural threat in human life, but it has been also producing a great many of artificial disasters, pollutants, chemicals, efficient tools for killing, etc. It can easily cause a great scale of accidental death in a moment. Scientific technology have brought on a new form of risk society in which we constantly living a risky life. Everyone living in such as technological society is inevitably being a risk-taker of death. The purpose of this article is to inquiry how we should treat accidental death caused by scientific technology. How should we treat the development of technology in the risk society? In order to response to these questions, I'll propose the moral principles of technology in a risky life and a study in life-and-death risk as well. The study in life-and-death risk involves the fundamental topics of life-and-death studies, the specialty of accidental death, the concept of death risk, and the risk assessment of death caused by technology.