Yan was born into an intellectual family, in Shanghai, on February 10, 1918. His father was a graduate of Peiyang University (now Tianjin University) and worked in the Beijing-Hankou Railway Administration as an engineer. His mother was an alumna of Hangzhou Woman Normal College.[3] Yan attended Beijing Chongde High School, during that time, he developed an interest in science and English. In 1935 he studied chemistry at the beginning in Tsinghua University, but transferred to Yenching University two year later. After graduation, he worked there as a teaching assistant under his mentor Zhang Zigao.
In 1941, the Pacific War broke out, because of the university suspended for the war, Yan was employed in Private China University alongside Zhang Zigao. The next year, he was employed in Tangshan Kailuan Refractories Company (唐山开滦耐火材料厂) as an engineer.
In 1946, he pursued advanced studies in the United States. Yan earned a PhD from the University of Illinois in 1949 and did postdoctoral work in the United States in 1950.[4] He returned to China later in 1950.[4]
He returned to China in 1950 and that year became a researcher at the Institute of Metallurgy and Ceramics of Chinese Academy of Sciences (CAS) (中国科学院上海冶金陶瓷研究所). Then he was promoted to director in 1954. He joined the Jiu San Society in 1956.[5] In 1960s he became the vice-president of the Shanghai Institute of Ceramics, Chinese Academy of Sciences (中国科学院上海硅酸盐研究所).
In 1976, Hua Guofeng and Ye Jianying overthrew the Gang of Four, he was rehabilitated. That same year, he served as president of the Shanghai Institute of Ceramics, Chinese Academy of Sciences and vice-president of the Shanghai Branch of Chinese Academy of Science. In 1977, he was invited to attend the National Working Conference on Science and Education (全国科教工作座谈会), which was presided by the comeback politician Deng Xiaoping. Yan was elected vice-president of the Chinese Academy of Sciences in 1981, and three years later promoted to First Vice-president and Party Group Secretary positions.
^严东生. Jiu San Society (in Chinese). 2015-12-15. Archived from the original on 2016-11-30. Retrieved 2016-09-26.
^我与材料科学大师严东生院士. Xinhua News (in Chinese). 2009-09-23. Archived from the original on November 12, 2014. 严先生虽然在文革中被戴上了"反动学术权威"的帽子,受到了很大的冲击,但他无怨无悔,他誓言要将耽误的时间追回来,于是他拼命的工作。
^ ab孙璧媃教授与交大化学一起走过的岁月. sjtu.edu.cn (in Chinese). 2009-11-26. Archived from the original on 2016-09-27. Retrieved 2016-09-26.