Zhenjin (Chinese: 真金; 1243 – 1285 or January 5, 1286), also rendered as Jingim, Chinkim, or Chingkim (Mongolian: Чингим/Chingim), was the second son of Kublai Khan and grandson of Tolui. He was designated as the Crown Prince (皇太子) of the Yuan dynasty by Kublai Khan in 1273, and became the head of the Central Secretariat (Zhongshu Sheng). The North Chinese Buddhist monk Haiyun gave him the name Zhenjin ("True Gold") when he was born in 1243. He was also known as a strong supporter of Confucianism. When a Confucian-trained official in the South proposed that Kublai abdicate in favor of Zhenjin in 1285, Kublai was angered. Zhenjin died on 5 January 1286, eight years before his father Kublai Khan.
According to the History of Yuan, he died of alcoholism. However, it may not have been as simple as merely drinking too much. It also stated that shortly before his death, some ministers of the court wanted to propose that Kublai Khan abdicate his throne to Prince Zhenjin on account of old age and because Zhenjin was highly respected throughout the empire. However, Zhenjin tried to prevent this from happening. Unfortunately, Kublai Khan found out anyway and was furious, which terrified Zhenjin and may have led him to overdrink. Distressed by his death, Kublai Khan made Zhenjin's son Temür the new Crown Prince, and Temür succeeded Kublai Khan in 1294 and became the Temür Khan or Emperor Chengzong.