Among the emperors of the Qing dynasty, some people were obsessed with the formula of elixir of life. Yong Zhengdi likes to be close to Taoist priests. He tried and took the elixir of life himself. He especially praised Ziyang real person, built a Taoist temple for him, and especially praised the real person for "inventing the essentials of the elixir of life". His favorite pills are Ji and Qiu. 1726 gave Ji Ji Dan to E Ertai, and the recipient reported "great curative effect" after taking it for one month. He also gave Ji to Tian Wenjing, saying that he was taking it continuously, and assured Tian Wenjing: "This Dan Xiu is exquisite and the effect is very different. Take it boldly, don't doubt it. This is a good medicine. I know best. " Yong Zhengdi once wrote the poem "Burning Dan": "Draw sand as medicine, pine and cypress around the cloud altar. The furnace contains yin and yang fire, both inside and outside. The light is shining, and the spirit protects the dragon. Consciously, the fairy fetus is ripe, and the fairy rhyme is purple. " Like many emperors in history, Yong Zhengdi kept many Dan families in his palace at that time, including Zhang Taixu, Wang Dinggan and others. On the third day after Yongzheng's death, Wang Ganlong, the new country, ordered the expulsion of Taoist priests such as Zhang Taixu and Wang Dinggan, indicating that the cause of Yongzheng's death may be Dan medicine poisoning.