Emperor Jin Huaidi 晉懷帝 (284-313, r. 306-311), personal name Sima Chi 司馬熾, courtesy name Fengdu 豐度, was a ruler of the Western Jin dynasty 西晉 (265-316). He was the 25-th son of the dynastic founder Sima Yan 司馬炎 (Emperor Wu 晉武帝, r. 265-290), and Lady Wang 王太妃, and was a younger brother of Emperor Hui 晉惠帝 (r. 290-306). Sima Chi's character is described as weak and delicate. In his younger years, he experienced the fratricidal conflicts within the imperial house. He had therefore no interest in political matters but instead began reading and enjoying pastimes.
In 290, he was made Prince of the Commandery of Yuzhang 豫章郡王 and was appointed General-in-chief of cavalry and chariots (cheji da jiangjun 車騎大將軍) or General-in-chief pacifier of the north ( 鎮北大將軍), a position in which he was supreme commander of the armies in the province of Qingzhou (dudu Qingzhou zhujun shi 都督青州諸軍事). He also held the civilian title of cavalier attendant-in-ordinary (sanji changshi 散騎常侍). In 304, Emperor Hui bestowed on him the title of Imperial Brother (huang taidi 皇太弟), which was close to that of Heir Apparent.
Two years later, he succeeded his brother to the throne. Sima Chi chose the reign motto Yongjia 永嘉 "Eternal Joy". His empress was Ms Liang 梁氏. Government was carried out by regent Sima Yue 司馬越 (d. 311), Prince of Donghai 東海王, who held the title of Grand Mentor (taifu 太傅) and was overseer of the imperial secretaries (lu shangshu shi 錄尚書事).
At that time, the internal strife between the court and the many members of the imperial house exploded in the Rebellion of the Eight Princes (ba wang zhi luan 八王之亂). In the same year, the Di 氐 chieftain Li Xiong 李雄 (274-334), controlling the Sichuan Basin, adopted the title of emperor of Cheng-Han 成漢 (304-347). This was the signal for the foundation of several counter-states in northern China during the next few decades, most of them proclaimed by non-Chinese leaders (see Sixteen Barbarian States).
The emperor sent out Sima Yue to protect the strategical city of Xuchang 許昌 (today in Henan). In 309, Sima Yue returned to the capital Luoyang 洛陽 (today in Henan) and massacred several high officials like Miao Bo 繆播 (d. 309), and requested the prestigious title of Minister of Education (situ 司徒). Not long thereafter, he fielded a new army and attacked Defender-in-chief (taiwei 太尉) Wang Yan 王衍 (256-311). The city of Luoyang was left without protection, and great turmoil broke out, not just among the people, but also in the various agencies of the central government. In Sichuan and Shaanxi, peasant rebellions under leaders Wang Ru 王如 and Du Tao 杜弢 broke out.
In 311, Sima Chi finally decided to charge Sima Yue with treason and ordered the local commanders, particularly Xun Xi 荀晞 (d. 311), to attack the prince, yet the latter died shortly after.
In this situation, the Xiongnu 匈奴 leader leader Liu Yao 劉曜 (d. 329), supported by the Jie 羯-Xiongnu Shi Le 石勒 (274-333) and the Chinese general Wang Mi 王彌 (d. 311), attacked Luoyang and besieged the city. People were starving, and historiographers report of cannibalism. In summer, Luoyang fell, and the soldiers of Liu Yao plundered the remains of the capital and massacred many thousand people (according to history books, more than 30,000 persons). Luoyang was burnt to the ground, and the emperor was taken captive. The turmoils of this year (Yongjia 5 永嘉) are known as the "chaos or disaster of the Yongjia reign-period" (Yongjia zhi luan 永嘉之亂, Yongjia zhi huo 永嘉之禍).
Sima Chi was brought to Pingyang 平陽 (today's Linfen 臨汾, Shanxi), where he was allowed to reside as Marquis of Ping'a 平阿公. In 313, the "emperor" of the non-Chinese Northern Han dynasty 北漢 (304-317), Liu Cong 劉聰 (r. 309-317), ordered Sima Chi to wear greenish clothes and serve the wine during a banquet. When the former Jin ministers began to weep, Liu Cong had the former emperor killed.
He was succeeded by his nephew Sima Ye 司馬鄴, known as Emperor Min 晉愍帝 (r. 313-316).