By explaining the natural science point of departure in the psychology of William James and examining the process of his investigations and breakthroughs, the paper argues that there is no doubt a fundamental turnabout in James’s psychological thinking. By further comparison with Edmund Husserl’s phenomenology, it points out that the potential theoretical significance of James’s psychological thinking can only be expressed and developed by borrowing from Husserl’s phenomenology his theoretical framework and conceptual instruments. The conclusion of the paper suggests the phenomenological turn in James’s psychological thinking greatly helps to understand psychology’s disciplinary identity and its theoretical reconstruction.