The disunity of morality and hapiness damages the social justice and sets back the sustainable development of morality.In order to maintain social justice,we must let "unity of morality and hapiness" become a relality and social value orientation.Because "unity of morality and hapiness" embodies three aspects:unity of morality and interest, unity of self-interest and altruism, equality of rights and obligations.To realize "unity of morality and hapiness", the effective way is to establish moral reward system