From 65438 to 0935, the North China Incident made the ethnic contradiction between China and Japan the main contradiction in Japanese society, which caused great changes in domestic class relations and international relations and the reorganization of various political forces. The policies of China's two largest political parties, the Producers' Party of China and the Kuomintang of China, have also changed accordingly. On June 10, the Shanghai Provisional Central Committee issued a declaration calling on party organizations at all levels to cooperate with all political and military factions that may oppose Chiang Kai-shek and resist Japan. 1 in August, the China * * * international delegation published a "Letter to All Compatriots for Resisting Japan and Saving the Country" (referred to as the "August 1 Declaration") in the name of the Central Committee of China and the Soviet Government of China, calling on the people of the whole country to unite, stop the civil war, resist Japan and save the country, and organize the national defense government and the anti-Japanese joint forces. In August and September of the following year, according to the further changes of the situation, the Central Committee of the Communist Party of China issued a letter to the Kuomintang and instructions on forcing Chiang Kai-shek to resist Japan, clearly proposing to realize the second cooperation between the two countries, forming a national anti-Japanese United front on the basis of the cooperation between the two parties, and changing the slogan of "resisting Japan and opposing Chiang Kai-shek" to "forcing Chiang Kai-shek to resist Japan". At this time, the Kuomintang Chiang Kai-shek clique was also forced to adjust its policies. After the Fifth National Congress of the Kuomintang in June 1935 1 1, the Chiang Kai-shek clique adopted a tough attitude towards the ongoing Sino-Japanese diplomatic negotiations. Adjusted the policy towards the Soviet Union. In connection with this, in June 1935+0 1, Chiang Kai-shek proposed "opening relations with the * * * production party". Under the above circumstances, starting from 1936, the two sides broke the deadlock of long-term opposition and sent representatives of both sides for secret contact through various channels.

In February, the Xi incident shocked China and foreign countries. The peaceful settlement of the Xi 'an Incident basically stopped the civil war between the two parties for 10 years, and created a prerequisite for the second cooperation between the two parties.

From February 9, 65438 to the end of September, 1937, representatives of both sides held six negotiations in An, Hang, Lushan and Nanjing. After more than seven months of repeated discussions, the Kuomintang finally agreed to reorganize the Chinese Red Army of Workers and Peasants into the Eighth Route Army of the National Revolutionary Army and recognized the Shaanxi-Gansu-Ningxia Border Region Government. On September 22nd, the Kuomintang Central News Agency published the Declaration on Central Cooperation between China and People's Republic of China (PRC). The next day, Chiang Kai-shek published the "Talk on the Manifesto of China Producer Party", in fact, announcing the recognition of the legal status of China Producer Party. At this point, the second national cooperation was formed.