This paper aims to explore John Wesley’s and early Methodist’s ecumenical spirit and practice at the time when we need more unity and cooperation of the Korean Protestant Churches hosting the 10th Assembly of the World Council of Churches, 2013. The writer examines his ecumenical spirit and practice in his Journal and Diaries, Letters, and Sermons etc. John Wesley, the founder of Methodism, was a man of ecumenical spirit and endeavored to take it into practice. In principle, he was a son of Church of England. However, he accepted other christian traditions, unless they didn’t hurt the essentials of christianity. His ultimate goal is to be sanctified and become a perfect Christian, not to be a member of a particular church or denomination. His ecumenical spirit drew on his characteristic stress on the true Christian’s interior life of holiness. His ecumenical central message is summed up as follows in the sermon, “Catholic Spirit”: “So far as in conscience you can (retaining still your own opinions and your own manner of worshipping God), join with me in the work of God, and let us go on hand in hand.” He insisted that “orthodoxy, or right opinions, is, at best, but a very slender part of religion, if it can be allowed to be any part of it at all”, but he also wrote that “A catholic spirit is not a speculative latitudinarianism. It is not an indifference to all opinion: this is the spawn of hell, not the offspring of heaven.” This study also demonstrates how difficult it was for John Wesley and early Methodist to realize their ecumenical spirit in the Methodist Movement which underwent the conflict and division between Wesleyan Methodist and Calvinistic Methodist espoused by George Whitefield. Despite their real differences, John Wesley emphasizes that Christians have a great deal in common and that they must stress and strengthen these existing bonds of unity. He preaches and practises in the 18th century what Christians in the twentieth have recently discovered and formulated. Taking it into consideration, he can be estimated as one of forerunners of modern ecumenical movement.