The research of rear area during the Anti-Japanese is lack of integrity and academic norms. In view of this situation, the author puts the rear area in the context of Chinese Anti-Japanese War and Word War II. This article makes an analytical study of the basic concepts, research subjects, historical status and roles, research value and research trend of rear area during the Anti-Japanese War, and it also considers and evaluates some important questions. During the period of Anti-Japanese War, rear area refers to the region of Chongqing-centric Western China. The research subjects include politics, economy, culture and society. The historical status and roles of rear area are represented in three dimensions. Firstly, the rear area, a main supporting area of Anti-Japanese War, has been the strategic rear of China. Secondly, it provided a political stage for the Anti-Japanese National United Front. In addition, it was the strategic pillar of Anti-Fascist War in the East. The research of the rear area will be helpful to fully recognize the significance and impact of the Second United Front. It would strengthen the idea of “The world belongs to the people, the supremacy of nation” (天下为公，民族至上) and promote the cross-strait reconciliation and unity. Rear area study could show the entire picture of Anti Japanese War, reflect the role and contribution of China more accurately during the war. In hope of new prospects in the China-Japan relations, we need to further unearth the truth about WWII and expose the atrocities of Japanese Army. In order to build a harmonious world, a new relationship between Sino-America should be established. For the purpose of achieving win-win cooperation between China and the world, we need to do further research on modern Chinese history, make Chinese academic achievements recognized by the world and enter into the mainstream of Western society.