This study discusses the developments of Judo for more than one hundred years. With it, we can understand Judo more. Looking back to the Judo rules and the historical changes can not only provide us with its whole developing process but also help us understand more about the influences in the contemporary Judo and the tendency to the future Judo developments. Besides that, we also look deeply into the organization and its function of International Judo federation, and set up an excellent and creditable function to make the referees judge more professionally and objectively in the future Judo competitions.