The 10th Assembly of WCC will take place in Korea in 2013. Conservative Evangelical churches in Korea take the negative ideas against the WCC. What is the theology of Ecumenical Movement? It is difficult to understand its theology. But it might be possible to catch the Ecumenical theological paradigm. Ecumenical movement produced the astonishing reports after a series of conferences or assemblies. Students who study the Ecumenical movement tend to be frustrated at its extraordinary documents. So I wonder whether any theological paradigm of the Ecumenical movement could be found. If so, we could grasp the total Ecumenical movement at a glace. According to W. A. Visser ‘t Hooft and Konrad Raiser, the Ecumenical movement in the first half of the twentieth century had a theological paradigm of ‘Christocentric universalism’, which had the four elements: Christocentrism, the concentration on the church, the universal perspective of world, and history-centered thought. As the head of church, Jesus Christ let the whole church participate in God’s salvation history to save the whole world. However, the Ecumenical movement in the second half of the twentieth century developed a new theological paradigm, which included the following four elements: Trinity and the kingdom of God, the deep study of the church, the radical study of the world (humanity) and the emphasis on the nature (creation). It could be said that God the Trinity as the Lord of the Kingdom of God let the whole church participate in the works of the Kingdom of God to save both the world (humanity) and the nature holistically. And the churches, as both sign and instrument of the kingdom of God, work to save the world (humanity) and the nature (creation) under the lordship of the Trinity. So we suggest its theological paradigm to be called as a ‘Trinity-centered universalism.’ As a conclusion, this study pointed up that the theological paradigm of the Ecumenical movement developed from Christocentric universalism to Trinity-centered one. Ecumenical movement took root in the ground in the Korean churches today. The Trinity-centered universalism as a Ecumenical theological paradigm could give the observers a coherent understanding and also provide every Ecumenical workers with a sense of solidarity.