Abstract: William James has been acknowledged as Father of American Psychology. James was the first in the history of psychology to integrate the previous psychological thoughts in his time and built an integrated psychology, which is conveyed in the discipline nature, subject matter, research methods and research topics in his psychology. James’ view on integration was “a view of star cluster”, which means differential unity. That is, psychological integration is pluralistic rather than monistic. After James, the phenomena of differentiation and disunity in the century-long history of psychology has aroused much attention of psychologists with insight. These psychologists raised the issue of integrating modern psychology again. James’ integrational view of psychology is essential intellectual resource for solving the integration problems of psychology, and has great significance on psychological research.