The article is devoted to the development of the diplomacy of Ancient China during the Warring States (Zhanguo). The material of the study were texts in Chinese, as well as works in Russian and Chinese. The article notes the growing role of the personality of the ambassador, diplomat. Particular attention is paid to the activities of two famous diplomats and strategists of the time, Su Qin and Zhang Yi. Su Qin is considered the founder of the idea of uniting the six kingdoms (Wei, Chu, Han, Qi, Zhao, Yan) into the anti-Qin alliance “vertically” (“hezong”) The merit of Zhang Yi is to create a pro-Qin alliance “horizontally” (“lianheng”) with the same kingdoms: Wei, Chu, Qi, Han, Zhao, Yan. The article provides a comparative analysis of the diplomatic activities of strategists Su Qin and Zhang I. The novelty of the study is that the activities of famous diplomats are examined through their use of “stratagems”. © 2021, Rossiiskaya Akademiya Nauk, Institut Istorii (Russian Academy of Sciences, Institute of General Hist. All rights reserved.