It is not known when Dou Yizhi was born, but it is known that his family was from the Tang capital municipality Jingzhao. His family claimed ancestry from the Han Dynasty official Dou Wu. His grandfather Dou Yuanchang served as a county magistrate, while his father Dou Yu served as a prefectural prefect. Dou Yizhi passed the imperial examination in the Mingjing class, and was made a copywriter at the Palace Library. He later passed a special imperial examination in judging cases, and was made the sheriff of Lantian County. He later successively served as Yousi Langzhong, a supervisorial official in the administration of the executive bureau ; Bingbu Langzhong, a supervisorial official at the ministry of defense ; and Libu Langzhong, a supervisorial official at the ministry of civil service affairs.
During Emperor Xianzong's reign
In 811, Dou Yizhi was made the deputy chief imperial censor. In 813, he was made an imperial attendant, and then made the governor of Shanguo Circuit. At a later point, he was made the mayor of Jingzhao. While he was serving at Jingzhao, there was an incident where Han Wu, the sheriff of Wannian County, one of the two counties making up the capital proper Chang'an, was found to have engaged in corruption. Dou ordered his subordinate Wei Zhengwu to investigate, and Wei found that Han had embezzled 300,000 coins-worth of money. Then-reigning Emperor Xianzong, however, did not believe that investigations were sufficiently thorough and ordered a reinvestigation; the reinvestigation concluded that Han actually embezzled 10 times the amount Wei reported. As a result, in 817, Dou was demoted to be the prefect of Jin Prefecture, while Wei was exiled. In 818, Dou was made the governor of Xuanshe Circuit, as well as the prefect of its capital Xuan Prefecture.
During Emperor Muzong's reign
In 822, by which time Emperor Xianzong's son Emperor Muzong was emperor, there was a mutiny at Xuanwu Circuit in which the soldiers expelled their military governorLi Yuan. Dou Yizhi heard about the mutiny and was concerned that his soldiers may be tempted to do the same. He considered passing out money and silk as rewards to them to endear them to him, but there was advice that doing so, without any reason, may in fact cause soldiers to fear that they were being suspected. He therefore did not do so, but rumors that he was passing out rewards already spread among the soldiers. One of the officers, Wang Guoqing thus plotted a mutiny. Wang's plot was discovered, and Dou executed Wang and over 200 of his coconspirators. He was thereafter replaced by Li Deyu and recalled to Chang'an to serve as the deputy minister of civil service affairs. Later that year, he was made the deputy minister of census and the acting director of finances.
During Emperor Jingzong's reign
Shortly after the death of Emperor Muzong and the ascension of Emperor Muzong's son Emperor Jingzong in 824, Dou Yizhi was made chancellor with the designation Tong Zhongshu Menxia Pingzhangshi, along with Li Cheng, apparently at the recommendation of the chancellor Li Fengji. He was thereafter made Menxia Shilang, the deputy head of the examination bureau of government while remaining as chancellor. He was also created the Duke of Jinyang, while being relieved of his post as director of finances. He was known for avoiding any appearances of nepotism, although years later, Emperor Jingzong's brother and successor Emperor Wenzong would comment, while speaking with the chancellors at that time:
During Emperor Wenzong's reign
In 828, by which time Wenzong was emperor, Dou Yizhi was relieved of his chancellor post and made the military governor of Shannan East Circuit as well as the prefect of its capital Xiang Prefecture, although he retained the Tong Zhongshu Menxia Pingzhangshi title as an honorary title. In 831, he was recalled to Chang'an to serve as Zuo Pushe, one of the heads of the executive bureau, as well as acting minister of worship. Later that year, he was made the military governor of Fengxiang Circuit as well as the mayor of its capital Fengxiang Municipality, and given the honorary title of acting Sikong. In 832, he requested a recall to Chang'an due to illness, and was recalled. He died in 833 and was given posthumous honors.
