It has all-important meaning for the right cognizing the moral essence and promoting the socialism moral development to scientifically define the concept of moral value. From the cross-perspective of the Value philosophy and Ethics, using the basic principles of Marxism, this article analyzes the six popular definition of moral value. After revealing their consensus, differences and major problems, on the basis of covering the consensus, giving a reasonable explanation of their differences and then answer the major problems, the thesis re-defines the meaning of moral value.