Roman Catholic Church gives the pope the highest authority to lead whole Catholic churches in the world and to decide theological and ecclesiastical issues, including its attitude to Islam. Therefore, in order to understand Roman Catholic Church's attitude to Islam, it is necessary to examine Benedict XVI(2005-2013)'s thought of religion and his understanding of Islam. The name of Benedict XVI is Joseph Ratzinger. As a professor Ratzinger taught Catholic theology in Bonn and Muenster. He was involved in the Second Vatical Council (1962-1965) as the reformer and admirer of Karl Rahner, Ratzinger was appointed to a chair at the University of Tubingen. After experiencing Marxist student riots in 1968, his theological position gradually was changed into conservatism. He served as professor and then as vice president of the University of Regensburg. He was appointed as Archbishop of Munich and Freising(1977-1982) and named as the Prefect of the Sacred Congregation for the Doctrine of the Faith(1981-2005). First, Benedict XVI wrote three encyclicals, "God is Love", "Saved by Hope", and "Love in Truth." He argues that religious freedom is needed for world peace. Distinguishing religious freedom from syncretism and religious pluralism, he emphasizes the uniqueness of Roman Catholic Church and considers the balance between faith and development of his theology of religions. Razinger rejects the positions of Karl Rahner and Hang Kung but accepts the necessity of religious dialogues and peace. He explains the evolution of religion and claims the finality of monotheism, which including Judaism,Christianity and Islam. He doesn't consider Islamic worldview seriously. Third, his conservative position is exclusive to other religions. He is suspicious of the possibility of inter-religious dialogue since the Roman Catholic Church cannot find a proper dialogue partner. There are many difference forms of Islam in the world, so he thinks that religious-dialogue is impossible in a real sense. It should be noted that Benedict XVI finds the common ground between Roman Catholic Church and Islam in the crisis of secularization. Muslims criticize the dualism of politics and religions in public areas of the West, which Benedict XVI regards as the particularity of Islam. Fourth, Benedict XVI‘s insulting lecture on Muhammad and Islam offended Muslim leaders to protest against his speech. Though he mentioned the expression of the Byzantine emperor Manuel II Paleologus, Muslims regarded his quotations as his own negative opinion against Islam. Pope gave public apology to Muslims in the world. After this accident, Benedict XVI met Saudi Arabia's king Abdullah in 2007 and Catholic-Muslim Forum was held in November 2008. In conclusion, there are many cases of Roman Catholic efforts to understand Islam with empathy and respect. Benedict XVI was the head of the Roman Catholic Church, but he didn't find the partner of Catholic-Islam Dialogue. Rather than doctrinal and theological dialogue, we should consider the possibility of new dialogues in social responsibility.