During the Second Sino-Japanese War, Xi stayed in the Yan'an Soviet to manage civilian and military affairs, boost economic production within the Soviet, and implement party policies. He was known for evaluating policies based on empirical assessment and resisting "leftist" extremism in implementing party directives. At the 7th National Congress of the Chinese Communist Party in August 1945, he was named an alternate member of the Central Committee and became the deputy director of the party's organization department, in charge of making personnel decision. As World War II in China was winding down, he defeated Nationalist attack on the Yan'an Soviet at Futaishan and assisted the breakout of Wang Zhen's 359 Brigade from the North China Plains.