In the 1940s, a horrifying war was sweeping the whole Europe. At the same time, particularly due to Freud’s death in 1939, another “war” broke out within the British Psychoanalytic Society, which had great influence on the development of psychoanalysis in British and all over the world. This war, known as the “Freud- Klein Controversies”, lasted almost four years from 1941 to 1945. It happened between two important pioneers of child psychoanalysis--Anna Freud and Melanie Klein--and their followers and loyal supporters, including Susan Isaacs, Paula Heinmann. During 1943 to 1944, a series of scientific meetings were held to solve the conflicts of the British Psychoanalytic Society, expecially between Anna and Klein. Due to their new psychoanalytic ideas different with Freud, Klein and her associates were asked to present papers to make their works clear. The four papers were “The nature and function of phantasy” (Isaacs, 1943), “Some aspects of the role of introjection and projection in early development” (Heinmann, 1943), “Regression” (Heimann & Isaaces, 1943) and “The emotional life and ego-development of the infant with special reference to the depressive position” (Klein, 1944). Then, the two psychoanalytic groups which were headed by Anna and Klein debated intensely on a serious of topics, such as unconscious phantasy, instinct and libido, and the training and education of the psychoanalyst candidates. As a result of the “Controversial Discussions”, a “Gentlemen’s Agreement” was signed and mediated by Sylvia Payne, and an agreement on the training of the psychoanalyst candidates was also made by the British Psychoanalytic Society and the Training Committee. That is, each candidate should first trained by A/B group that they belonged to, and then be supervised by another member from the Independent group which was not the same with A/B. What’s more, “Controversial Discussions” also directly led to the triangle situation of the British psychoanalysis, which constituted of Kleinian group, Vienna group and Independent group. The “Controversial Discussions” was labelled as “struggle without mercy”, “bitter combat” and “incredible”, but it is also “the most important period of the history of psychoanalysis in Great Britain” and “the successful attempt to contain in a creative and tolerant way enormous tensions and dissensions of all sorts by means of a sort of hermeneutic dialogue and comparison of different views”. In conclusion, this debate promoted the separation of psychoanalytic schools between object-relation and ego psychology, proceeded the paradigm shift of psychoanalysis from drive model to relational model, and established the pattern of the following development of psychoanalysis. As Steiner said, some of the problems discussed and the resolutions proposed by the Training Committee of the British Society during the years of the Controversies......are still a source of food for thought today, in spite of the fact that they belong to a specific past. Learning from this historical event of “Controversial Discussions”, we think that emphasizing the interaction and integration of various ideas rather than disagreements and disputes is the only way that psychoanalysis can go further in the competing environment. We can assert that psychoanalysis will encounter a lot of difficulties in the future, meanwhile it is sure to develop constantly.