Emperor Jin Mingdi 晉明帝 (r. 322-325), personal name Sima Shao 司馬紹, courtesy name Daoji 道畿, was a ruler of the Eastern Jin dynasty 東晉 (317-420). He was the oldest son of Emperor Yuan 晉元帝 (r. 317-322), and his mother hailed from the Xun family 荀氏.
Sima Shao was known for his literary talent and his cultivation in both civilian and military matters. He was therefore the favourite son of Emperor Yuan (at that time still Prince of Jin 晉), who therefore gave him the title of Leader of the eastern court gentlemen (dong zhonglangjiang 東中郎將). In 318, when his father acceded to the throne, Sima Shao was made imperial heir apparent (huang taizi 皇太子).
When general Wang Dun 王敦 (266-324) rebelled, Emperor Yuan desired to exchange the heir apparent, but the ministers remonstrated successfully against this step. In 322, Sima Shao succeeded his father to the throne, and chose as his regent Wang Dao 王導 (276-339), who held the honorific title of Minister of Works (sikong 司空) and was a cousin of Wang Dun. A year later, Yu Wenjun 庾文君 (297-328) was chosen empress of Sima Shao. She was a younger sister of general Yu Liang 庾亮 (289-340).
Wang Dun had meanwhile reached the position of regional governor (mu 牧) of the province of Yangzhou 揚州, with his seat in Gushu 姑熟 (today's Dangtu 當涂, Anhui). In 324, he made his son Wang Ying 王應 (d. 324) General of martial defense (wuwei jiangjun 武衛將軍) and his older brother Wang Han 王含 (d. 324) cavalry general (piaoji jiangjun 驃騎將軍). Wang Dun killed the emperor's most trusted ministers like Ran Zeng 冉曾 and humilitated the sovereign by ordering him to his camp. Yet Sima Shao used this occasion to investigate the general situation of the rebel. He appointed Wang Dao area commander-in-chief (da dudu 大都督) and took first measures for a counterstrike, supported by ministers as Yu Liang and Wen Jiao 溫嶠 (288-329). Su Jun 蘇峻, governor (taishou 太守) of Linhuai 臨淮, and Liu Xia 劉遐 (d. 326), regional inspector (cishi 刺史) of the province of Yanzhou 兗州, were ordered to transfer their troops to the capital Jiankang 建康 (today's Nanjing 南京, Jiangsu) for defense. Yet shortly later, Wang Dun died, and his army dispersed into all winds. Sima Shao returned to the capital and rewarded his supporters richly.
In 325, he reintroduced the punishment by collective liability in three generations (sanzu 三族), but with the exemption of females. When he fell ill, the emperor appointed his son Sima Yan 司馬衍 heir apparent and entrusted a group of ministers with government affairs. Sima Shao died not long thereafter.
He was succeeded by his oldest son Sima Yan, who is known as Emperor Cheng 晉成帝 (r. 325-342).