Abstract: As a theoretical approach different from utilitarianism and deontology, virtue ethics, which rises in the contemporary era, is agent-centered. agent-centered approach involves how to interpret or understand behavior and emotion with the concept of virtue. Virtue is the intrinsic character traits relatively stable of the agent who behaves and feels in the world of moral phenomena. With the agent-centered virtue ethics not only regards behavior as a single atomic behavior, but also internally correlates behavior and emotion with the agents. Returning to the agents themselves, we need to answer why human beings need virtue. Virtue ethics holds that the intrinsic relationship between agent’s happiness and virtue is emphasized, although Aristotle’s ethics does not deny that external goods have the status of the concept of happiness. However, only to see the intrinsic relationship between virtue and the happiness of the agents has not yet answered an important question: virtue sometimes requires self-sacrifice. To answer this question, we should look at virtue beyond the perspective of self-happiness. Contemporary virtue ethics uses ethical naturalism to explain the problem that human beings need virtue. In MacDowell’s opinion, he put forward the concept of “second nature”, while Hurstwood put forward ethical naturalism of quadruple functional-ends based on Aristotle’s naturalism. To return to agent’s in itself, which is one direction of development norm theory.