Death penalty is the most effective deterrence to grave crimes, which has been the key basis for the State to retain death penalty. In fact, either in legislation or in execution, death penalty can not produce the special deterrent effect as expected. With respect to this issue, people tend to conduct normative exploration from the perspective of ordinary legal principles or the principle of human rights, which is more speculative than convincing. Correct interpretation based on the existing positive analysis and differentiation based on human nature which sifts the true from the false will not only help end the simple, repetitive and meaningless arguments regarding the basis for the existence of death penalty, but also help understand the rational nature of both the elimination and the preservation of death penalty, so as to define the basic direction towards which the State should make efforts in controlling death penalty in the context of promoting social civilization.