Collected Illustrations of the Three Realms: Personalities, Volume 7

Lü Mengzheng, whose courtesy name An adult name given in addition to one's given name, used as a mark of respect among peers was Shenggong, was a native of Henan. In the second year of the Taiping Xingguo Taiping Xingguo (976–984 AD), an era name of the early Song Dynasty under Emperor Taizong era, he was promoted to first place in the Jinshi Jinshi (literally "presented scholar"), the highest degree in the imperial examination system examinations.

He served as the Vice-Prefect of Shengzhou and was successively promoted to the positions of Left Palace Censor and Drafter of Edicts. Upon the death of his father, he entered a period of ritual mourning original: "丁父憂"; the traditional Chinese practice where an official retired from public life for up to three years to honor a deceased parent. He was later recalled to service and promoted to Director in the Ministry of Justice, eventually entering the Hanlin Academy Hanlin Academy, an elite institution of scholars who performed secretarial and literary tasks for the Emperor as a Scholar.

Lü was further promoted to the rank of Left Remonstrator. When the official Li Fang was dismissed from the Chancellorship, Lü was appointed as Vice-Director of the Chancellery. While in office, he was known for a character that was honest, kind, lenient, and straightforward. He dared to speak his mind whenever issues arose, and the Emperor praised him for having no hidden agendas. Since the founding of our dynasty, the only individuals to have served as Chancellor on three separate occasions have been Zhao Pu and Lü Mengzheng.