Educational ethics belongs to the value practice science in the field of applied ethics. The value function of educational ethics lies in giving full play to the noumenon value of education, better satisfying people's demand for education, and truly enhancing people's life essence and influence in education. This reflects the ultimate value concern of educational ethics. Its rationality is based on the law of development of education itself, the law of human development, the law of social development and the concept of goodness.