Abstract: On December 11, 1937, the only comprehensive theoretical journal—The Masses weekly was publicized by the CPC in the Kuomintang ruled area during the Anti-Japanese War. The publication of the The Masses weekly was not only the result of the CPC’s long struggle for freedom of speech and other rights, but also the product of the second cooperation between the KMT and the CPC in the outbreak of the Anti-Japanese War. Although the The Masses weekly was able to be established in the Kuomintang District, its publishing and distribution were constantly hindered, disturbed, and destroyed by the KMT. The difficult founding process of The Masses weekly, and its irregular publication, and distribution during the period of the Anti-Japanese War proved that its growth was closely related to the relationship between the KMT and the CPC. In other words, The Masses weekly was a barometer of the relationship between the KMT and the CPC throughout the Anti-Japanese War.