The death of Emperor Qin Shi Huang is a big mystery. It is known that he died in 210BC in Shaqiu Palace (in today's Guangzong County, Xingtai City, Hebei Province), but no further explicit record can be found. Shaqiu Palace was a desolate place where anything might have happened, which adds more mystery to this riddle. Therefore, since ancient times, people have come up with a variety of theories to explain his death. At present, two theories are favored. The first one is that he died of an illness, and the second one is that he was murdered. 
Qin Terracotta Army
People who support that he died of an illness believe he suffered from overwork. Every day, during his reign, he had to scrutinize a large number of documents and attend to every petty detail personally to ensure the preservation of imperial power. Being the first emperor in Chinese history and the builder of a centralized system, Qin Shi Huang had no precedent to follow but still had full responsibility. Overwork brought on a serious illness to this industrious emperor. In addition he went on five big tours in 12 years. Even taking the most advanced highway "Chi Dao" of the time, he suffered badly from being jolted on the bumpy roads all the time. The luxurious chariot he took cannot be compared with the car, bus and train of the modern world. Therefore, the emperor must have gone through great hardship in his long royal procession. His final trip started during a severe winter and ended in hot summer - the great change of weather might have increased his chance of disease. Also he had more than 10,000 concubines and probably was frequently active in bed, which might have damaged his health.
Though the possibility that Qin Shi Huang's died of an illness has been deeply analyzed, some people refute this. The emperor was not weak like many other emperors in history. No historical record on his illness has been found. His successful sprinting escape from Jing Ke's assassination attempt is a good example of his strength. As a result, some people think murder is more likely and mention three people suspected to have been connected with the crime. They are Hu Hai, Zhao Gao and Li Si.
Hu Hai's involvement is doubtful. He was the son of Qin Shi Huang. After learning of his brother Fu Su's succession to the throne, he might have felt dissatisfied and killed Qin Shi Huang to vent his anger. But this presumption cannot stand firm because the rescript and royal seal were kept by Zhao Gao, whom Qin Shi Huang trusted most when he was ill. Without Zhao Gao's cooperation, Hu Hai still could not ascend to the throne even though he killed his father. Zhao was always by the side of Qin Shi Huang, therefore had more opportunities to kill the emperor. Li Si, the prime minister of Qin Dynasty, was also more likely to be the murderer, for he could keep his official position by hailing Hu Hai a new emperor after Qin Shi Huang died. 
Qin Terracotta Soldier
In folk legend, Emperor Qin Shi Huang died of a people's curse due to his tyrannical government. Of course, this is the most absurd hypothesis only showing the people's hatred of the emperor. Though the assertions are all logical they are unproved by any historical record or unearthed cultural relics. The death of the first emperor still remains a matter of question.
Travelers' Voices on Death of Emperor Qin Shi Huang
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Oct. 30,2009 12:54 Reply
Mrs.Wagner(Usa) said:
It was awesome!!!!!!!!!!!!!!!!!!!
2.
Oct. 28,2009 16:07 Reply
Ms.Shelby(Indiana) said:
Qin Shi Huang Di was a man who was obsessed with immortality. His prime ministers and other palace healers made him a pill to take that contained too much mercury in it and he died from organ failure, mostly kidney and liver. None know how or why he became so obsessed with immortality, but scholars assume that the mercury and other various drugs in the pill cause Qin Shi Huang Di to become paranoid and start hallucinating. Few knew of this, and those that did kept it secret because they were members of the Rebels: they didn't like the way Qin Shi Huang Di was so cruel and strict. The few members of the Rebels that did know later were found out about and executed for high treason. They were executed using Qin Shi Huang Di's favorite method: torn apart from limb to limb by horses. You litterally had your arms and legs torn from your torso and you died from lack of blood. The death of Qin Shi Huang Di is only labeled as a mystery because few know of the real storry of what happened to the emperor and his decendents. Scholars believe that his decendants were later assassinated.