In 706, his younger brother provided Li Xian with an honorable burial by interring his remains at the Qianling Mausoleum.
Li Xian was born in 653, as the sixth son of and the second son of his then-favorite concubine . There were, however, persistent rumors inside the palace that he was not actually born of Consort Wu but of her older sister . In 655, the same year that his mother Consort Wu displaced Emperor Gaozong's first wife as empress, Li Xian was created the Prince of Lu. In 656, he was initially titularly given the post of prefect of Qi Prefecture , and then the dual posts as prefect of the capital prefecture Yong Prefecture and commandant at You Prefecture . It was said that his behavior was elegant, even in his youth, and, according to a comment that Emperor Gaozong made to the , he studied the ''Classic of History'', ''Classic of Rites'', ''Analects'', and a number of ancient poems and could remember them clearly. In 661, his title was changed to Prince of Pei, and he was given the titles of commandant at Yang Prefecture and major general, but continued to also serve as prefect of Yong Prefecture. At this time, he had the literarily-talented official Wang Bo on staff. Around this time, the princes were apparently often engaged in cockfighting. Wang Bo wrote a playful piece entitled the ''Declaration Against the Prince of Zhou's Cock'' , which, however, when Emperor Gaozong read it, caused Emperor Gaozong to be angry, as he believed this would cause discord between his sons, and therefore expelled Wang from the Pei mansion. In 672, Li Xian's title was changed to Prince of Yong, and he was given the titles of commandant at Liang Prefecture , but continued to also serve as general and prefect of Yong Prefecture. His name was also changed to Li De. In 674, his name was changed back to Li Xian.
As crown prince
In 675, Li Xian's older brother Li Hong the crown prince died -- a death that traditional historians generally believed to be a poisoning ordered by Empress Wu. On July 3, Li Xian was created crown prince to replace Li Hong. Emperor Gaozong soon ordered that much of government matters be ruled on by Li Xian, and Li Xian was praised for making good decisions. Also around this time, Li Xian led a group of scholars, including Zhang Da'an, Liu Nayan , Ge Xiyuan , Xu Shuya , Cheng Xuanyi , Shi Cangzhu , and Zhou Baoning , in writing commentaries for the ''Book of Later Han'', the official history of the Eastern Han Dynasty, written by the Liu Song scholar Fan Ye.
Meanwhile, Li Xian's relationship with Empress Wu began to deteriorate, as Li Xian had heard the rumors that he was actually the son of Lady of Han, and had become fearful. Empress Wu, detecting this, had her literary staff write two works entitled, ''Good Examples for Shaoyang'' and ''Biographies of Filial Sons'' and gave them to Li Xian, and further wrote a number of letters rebuking Li Xian, making him more fearful. Further, when the sorcerer Ming Chongyan , who was well-trusted by Emperor Gaozong and Empress Wu, was assassinated in 679, Empress Wu suspected Li Xian -- as Ming had been known to repeatedly make comments to Empress Wu that included, "The Crown Prince cannot bear the responsibilitiies of state. The Prince of Ying has an appearance most similar to ," and "The Prince of Xiang has the most honorable appearance."
Meanwhile, Li Xian was also known for his liking of music and women. When Empress Wu heard this, she had people report this to Emperor Gaozong, who ordered an investigation led by the officials Xue Yuanchao, Pei Yan, and Gao Zhizhou. When they searched the crown prince's stables, they found several hundred black armors, and they believed this to be evidence of a coup, and after interrogation, one of Li Xian's favorite servants, Zhao Daosheng , admitted to assassinating Ming on Li Xian's orders. Emperor Gaozong, who had favored Li Xian, considered pardoning him, but Empress Wu refused. On September 20, 680, Emperor Gaozong deposed Li Xian and reduced him to commoner rank, delivering him from the eastern capital Luoyang to the capital Chang'an to be imprisoned there. His close associates were executed, and the armors seized were publicly burned to show the people that, in fact, Li Xian had committed treason. Li Zhe was created crown prince to replace him.
in 683, Li Xian was moved from Chang'an to Ba Prefecture . In 684, after Emperor Gaozong's death, Li Zhe initially took the throne , but soon was deposed himself due to signs of disobedience to Empress Wu , and Li Dan became emperor instead , although Empress Dowager Wu retained all powers as regent. In spring 684, she sent the general Qiu Shenji to Ba Prefecture with the order of, "Examine the house of Li Xian the former crown prince to prevent external attacks." However, she hinted to him that he should have Li Xian killed. When he got to Ba Prefecture, he placed Li Xian into a small room and forced him to commit suicide. When news of Li Xian's death arrived at Luoyang, Empress Wu publicly blamed Qiu and demoted him to the post of prefect of Die Prefecture , while publicly morning Li Xian and posthumously creating him the title of Prince of Yong. After Empress Wu's death in 705 and the restoration of Emperor Zhongzong to the throne, Emperor Zhongzong had Li Xian's casket returned to Chang'an, to be buried near the tomb of Emperor Gaozong. After Emperor Ruizong became emperor again in 710, he had Li Xian's crown prince title restored.