Liu Ji (Chinese: 劉濟; 757 – August 20, 810[1]), courtesy name Jizhi (濟之),[2] was a general of the Chinese Tang dynasty who served as the military governor (jiedushi) of Lulong Circuit (盧龍, headquartered in modern Beijing) from 787 (succeeding his father Liu Peng) to his death in 810, when he was poisoned by his son Liu Zong during an imperially-sanctioned campaign against neighboring Chengde Circuit (成德, headquartered in modern Shijiazhuang, Hebei).
[6] Liu Ji served as the prefect of Mo Prefecture (莫州, in modern Cangzhou, Hebei) under his father.
[8] While the military governors of the region were generally ruling their circuits de facto independently from the imperial regime at the time, Liu Ji was said to treat Emperor Dezong with respect, often offering tributes, and Emperor Dezong also treated him with respect, making him honorary minister of defense.
By 792, Liu Yong, displeased, directly submitted to Emperor Dezong and contributed soldiers to the winter defense against Tufan to the west of Chang'an.
Liu Ji's emissary to Weibo Circuit (魏博, headquartered in modern Handan, Hebei), Tan Zhong (譚忠), was able to persuade Weibo's military governor Tian Ji'an not to join Chengde's cause, and then persuaded Liu Ji himself to attack Chengde—pointing out that if he did not, Emperor Xianzong would believe that he was complicit in Wang Chengzong's resistance.
In spring 810, Liu Ji thus launched his own campaign against Chengde, capturing a number of towns.
As Liu Ji was at Raoyang (饒陽, in modern Hengshui, Hebei), he grew ill.