Li Deyu was a native of Emperor Zanhuang of Zhao County (present-day Emperor Zanhuang, Hebei), and because his father Li Jifu was a Zhongshu waiter, he grew up reading poetry under the influence of his father and had great ambitions. However, Li Deyu did not like to participate in the scientific expedition, and it was because of family reasons that he was able to enter the career.
Since he was a child, Li Deyu has shown his extraordinary qualifications, and many people, including Tang Xianzong, have been very praised by him, and Tang Xianzong often held him on his lap. After entering the army, because his father Li Jifu was promoted to the position of prime minister, in order to avoid suspicion, Li Deyu went to the town to take up a post. In the fifteenth year of Yuan He (820), after being summoned to the Hanlin Academy as a Hanlin scholar, he had a deep friendship with Li Shen and Yuan Shu, and all three of them were talented, so they were called "Three Juns" by the people at that time. After that, Li Deyu's career was relatively smooth, and he successively served as a Tuntian Member Wailang, Kao Gong Lang Zhong, Zhi Zhi Zhen, and Zhongshu Sheren.
In the Middle and Tang Dynasties, the two factions of the Niu Dang and the Li Dang above the imperial court began a nearly forty-year-old partisan struggle, which is the famous "Niu and Li Dang Controversy" in history. Because niu monks and children and Li Zongmin participated in the scientific expedition was a needle in the needle, the examiner recommended them to Tang Xianzong, and Li Jifu, who was the prime minister at the time, went to Tang Xianzong and cried in front of Tang Xianzong and complained that Niu and Li had exposed their shortcomings, believing that they had an affair with the examiner. Therefore, Tang Xianzong demoted the examiner and did not promote Niu and Li. Unexpectedly, there was an uproar in the court, and the ministers all cried out for Niu Li, and believed that Li Jifu was jealous of his ability and had no choice, so Tang Xianzong demoted Li Jifu to the position of envoy of Huainan Jiedushi.
After that, both Niu monks and children and Li Deyu entered the dynasty as officials, and with Li Jifu's affair as the fuse, Niu monks and children and others formed a faction with officials from the Imperial Examination, and Li Deyu and others formed a faction with officials from the scholar clan. When the Bull Party gained power, it took the opportunity to attack the Li Party; when the Lee Party gained power, it also took the opportunity to squeeze out the Bull Party, and even the emperor felt a headache in the open struggle between the two factions. However, after Tang Xuanzong succeeded to the throne, Li Deyu lost power, and the Niu Dang took the opportunity to vigorously exclude Li Deyu, causing Li Deyu to be demoted to an idle official.
However, Li Deyu did not focus on the dispute of expansion in the DPRK and China, and also did a lot of practical things. During the Poly years, the bozhou area is said to produce holy water to cure all diseases, so that sick people can drink it and be cured. The news came and went, more and more like the truth. Li Deyu gathered the people in the big market, let people fill the pot with the so-called holy water, and put five catties of pork into it to cook, Li Deyu said to the people: "If this is really holy water, the pork will not change in any way!" After a while, the pork was cooked and the rumors subsided.
In the sixth year of Taihe (832), Emperor Wenzong of Tang recalled Li Deyu and made him a soldier shangshu, and a year later he was honored as the chancellor. However, the good times did not last long, and Li Deyu was ostracized by the traitors because of his integrity, and he was degraded. It was not until the fifth year of Kaicheng (839) that Emperor Wuzong of Tang succeeded to the throne and recalled Li Deyu from Huainan to pay homage to the chancellor. Coincidentally, Li Deyu's father, Li Jifu, both of them went out to Huainan at the age of fifty-one, and at the age of fifty-four, they were recalled to the court and worshiped each other again. In the next five years, Li Deyu returned to Qi, NeiPingzelu, dismissed redundant officials, made eunuchs, and performed outstanding feats, and was also worshiped as a lieutenant and given the title of Duke of Zhao. During this period, Tang Wuzong and Li Deyu's monarchs and courtiers also became the last song of the late Tang Dynasty. After Emperor Wuzong of Tang died of illness and was succeeded by Emperor Xuanzong of Tang, Emperor Xuanzong of Tang had always hated Li Deyu, and with the rumors of his traitors, Li Deyu was demoted to Death in Yazhou.
It is said that once Li Deyu was like a monk who inquired about the past, the monk said that he would be reprimanded, but he would still be recalled, and said that Li Deyu was destined to eat ten thousand sheep in his life, and there were still five hundred sheep that had not been eaten, so he would be able to return to the imperial court again. More than ten days later, zhenwu jiedushi sent Li Deyu five hundred sheep, and he was so frightened that he asked the monk, "Can I avoid disaster if I don't eat these sheep?" The monk said, "The sheep have been delivered, even if you do not eat them, they are already yours." Soon Li Deyu was indeed flattened to Yazhou and died there. Later generations used the allusion of "eating ten thousand sheep" to indicate resignation to fate and no need to force wealth.