Emperor Han Aidi 漢哀帝 (r. 7-1 BCE), personal name Liu Xin 劉欣, courtesy name Xi 喜, was one of the last rulers of the Former Han period 前漢 (206 BCE-8 CE). He was a grandson of Emperor Yuan 漢元帝 (49-33 BCE), a son of Prince Gong of Dingtao 定陶恭王 and Lady Ding 丁姬. He succeeded his uncle Emperor Cheng 漢成帝 (r. 33-7 BCE) to the throne.
As a young boy he was fond of literature and the law code. He was named heir apparent when it was clear that Emperor Cheng would not have any sons. Liu Xin mounted the throne when he was 20-sui old. His empress was a Lady Fu 傅氏, the secondary consort was Lady Dong 董昭儀, the sister of Emperor Ai's favourite Dong Xian 董賢.
Emperor Ai was a very weak ruler and left all decisions in government to Dong Xian, allowed him to ride in the same cart with the emperor, to be assisted by a large entourage, and to live in the largest mansion in the capital. Dong Xian's father was appointed Chamberlain for the Palace Revenue (shaofu 少府) and ennobled as Marquis within the Passes 關内侯. Emperor Ai even deliberated making Dong Xian his successor to the throne.
This circumstance lead to Bao Xuan's 鮑宣 famous memorial to the throne pointing at the suffering of the common people (the "seven vanishings" and "seven deaths", qi wang qi si 七亡七死) and the luxurious way of life that the large landowners lived. He suggested limiting the size of land a private person could own, as well as the number of slaves a private persons could dispose of. Yet such a law would restrict the endless power of the families Ding 丁 and Fu 傅, to which Emperor Ai's mother, Lady Ding, and his own empress belonged, and therefore such a law was never brought into shape.
During the reign of Emperor Ai, some astrologers like Gan Zhongke 甘忠可 stressed that it was important to create a new calendar in order to revive the Heavenly Mandate (tianming 天命) bestowed to the emperors of the Han dynasty. In 5 BCE therefore, the new Taichu calendar "Grand Beginning" was enacted (Taichu li 太初曆, correct name Taichu yuanjiang li 太初元將曆). Emperor Ai adopted the new title of Chensheng Liu Taiping huangdi 陳聖劉太平皇帝 "Emperor of Great Peace from the Saints of the Family Liu", but after a month he gave up this voluminous title and even had some of his adisors put into jail.
In 6 BCE, the Confucian scholar Liu Xin 劉歆 suggested establishing the position of erudite (boshi 博士) for the old-text Shangshu 古文尚書 "Book of Documents", but he was heavily criticized by the adherents of the new-text school of Confucian Classics. This was the beginning of the factional strife between the representatives of the two schools of old-text and new-text classics that interpreted the old venerated texts in two different ways.
In 2 BCE the first Buddhist sutra arrived in China, still in an oral form, by way of a scholar named Jing Lu 景廬 or Qin Jingxian 秦景憲 who had stayed in the country of the Tokharians (Chinese name Yuezhi 月氏).
Emperor Ai was buried in the tomb mound Yiling 義陵. He was succeeded by Liu Kan 劉衎, who is known as Emperor Ping 漢平帝 (r. 1 BCE-5 CE).