Du Ruhui was born in 585, during the reign of Emperor Wen of Sui. He was from the Du clan of Jingzhao, which came from the region around the capital Chang'an. His great-grandfather Du Jiao and grandfather Du Hui were both officials for Sui's predecessor stateNorthern Zhou, and his granduncle Du Guo or Du Gao was particularly well-regarded during Sui. His father Du Zha was a provincial secretary general during Sui. Du Ruhui had at least one older brother, whose name is lost to history, and one younger brother, Du Chuke. Du Ruhui himself was considered intelligent in his youth, and he often discussed literature and history with others. During Emperor Wen's reign, he participated in the civil serviceselection process, and the deputy minister of civil service affairs, Gao Xiaoji, was particularly impressed with him. Gao gave him the post as a county magistrate, although Du did not remain at that post for long and resigned.
During Emperor Gaozu's reign
In 617, the governor of TaiyuanLi Yuan rebelled against the rule of Emperor Wen's son Emperor Yang, and by 618 had established the Tang Dynasty at Chang'an. Du Ruhui served on the staff of Emperor Gaozu's son Li Shimin the Prince of Qin, a major general. At that time, Li Shimin had many talented people on his staff, and soon, many were commissioned to be local officials. Du was scheduled to become the secretary general for Shan Prefecture, when Li Shimin's trusted advisor Fang Xuanling pointed out that Du was highly talented and that Li Shimin could not afford to lose him. Li Shimin thus interceded with Emperor Gaozu to keep Du on his staff. Du later followed Li Shimin in campaigns against Tang's major enemies Xue Rengao the Emperor of Qin, Liu Wuzhou the Dingyang Khan, Wang Shichong the Emperor of Zheng, and Dou Jiande the Prince of Xia, contributing strategies to LI Shimin's campaigns. For his achievements, Du was created the Baron of Jianping. .
During Emperor Taizong's reign
Late in 626, when Emperor Taizong personally ranked the contributions of the generals and officials in order to grant them fiefs, Emperor Taizong ranked five of them—Fang Xuanling, Zhangsun Wuji, Du, Yuchi Gong, and Hou Junji to be contributors of the highest grade, and Du was created the Duke of Cai. When Emperor Gaozu's cousin Li Shentong the Prince of Huai'an, himself a key general, objected to being ranked below Fang and Du, stating that Fang and Du, in particular, were only bureaucrats, Emperor Taizong pointed out that it was with their strategies that he was able to become emperor, Li Shentong relented, which led to the other objectors to also cease their objections. In 629, Du, along with Fang, became Puye, a head of the important executive bureau of the government and a post considered one for a chancellor. It was said that at this time that the Fang and Du became known as the model for chancellors. During this time, remembering Gao Xiaoji's kindness toward him, he commissioned a stone tablet monument for Gao. Around the new year of 630, however, Du resigned due to illness. By spring 630, he was near death. Emperor Taizong initially sent his crown princeLi Chengqian to visit Du, and then did so himself as well. Du soon died. For a long time, whenever Emperor Taizong received precious items, he would think of Du, and he would send messengers to deliver some of the items to Du's family. He also often wept while talking with Fang, stating, "Both you and Du Ruhui assisted me. Now I only see you, and not him." For reasons unclear, he changed Du's title posthumously to Duke of Lai, with the posthumous name Cheng. He gave his daughter Princess Chengyang to Du's son Du He in marriage and created Du He the Duke of Xiangyang. In 643, when Emperor Taizong commissioned the Portraits at Lingyan Pavilion to commemorate the 24 great contributors to Tang rule, Du's was one of the portraits commissioned. However, the honored position of the Du clan did not last long. Later in 643, Du He was implicated in a plot with Li Chengqian to overthrow Emperor Taizong. Du He was executed, while Du Gou was exiled.
