Yin Defai was the favorite concubine of Gaozu in his later years, because she was beautiful. Yin Defai became pregnant and gave birth to her son Li, which won her favor. Politically, in order to consolidate their position and self-interest, Yin Defai and Li Yuanji colluded with Prince Li and secretly hooked them up as traitors, wantonly indulged in lewdness and slandered for murder. Li and Li Yuanji were good at doing good deeds and bribed Yin Defai and their two common mothers to put in a good word for themselves in front of Gao-zu. For example, The Book of the Old Tang Dynasty said that Li and Li Yuanji had an affair with the concubine Yin Defai and committed adultery in the harem, and immediately investigated the four of them for adultery.

Yin Ashu, the father of Yin Defa, was arrogant, and Du Ruhui, the subordinate of Li Shimin, the king of Qin, passed by Yin Ashu's house. Uncle Yin's servant dismounted and said to Du Ruhui, "Who dares to cross our door and not dismount!" After a beating, Du Ruhui's finger was broken, but the wicked Rat Yin complained first and asked Yin Defa to falsely accuse Du Ruhui of bullying his servant to Tang Gaozu. Gaozu angered Li Shimin: "My concubines are bullied by people around you, let alone ordinary people!" Li Shimin has repeatedly defended himself, but Gaozu never believed him. Later, Li, Li Yuanji, Yin Defa and even conspired to kill. After the change of Xuanwu Gate, Yin Defa and Zhang Jieyu disappeared. Li only knew that in the second year of Zhenguan (628), her son was granted a regular attendance on scattered riding and worshipped as a secretariat of Jinzhou.