The purpose of this paper is to analyze the factors that led to Emperor Gaozong of Song's 宋高宗 appointment of Lü Yihao 呂頤浩 as the prime minister. In the past, scholars believed that the key factor was Lü Yihao's success in putting down the mutiny launched by Miao Fu 苗傅 and Liu Zhengyan 劉正彥. By this view, therefore, there was obviously an incidental element in his appointment.. However, after Emperor Gaozong ascended to the throne, he summoned Lü Yihao for an audience in Yangzhou 揚州. This explains two things: first, they might have had an earlier acquaintance, and second, Lü Yihao had the qualification of being a wartime prime minister 戰時宰相. The author's research shows that as early as the final years of the Northern Song dynasty, they were detained by Jurchen, and spent a period of time together when they got to know each other, and cultivated an intimate friendship.paving the way to the appointment of Lü Yihao as the prime minister.