Zhai was born in
Liyang County (now Liyang),
Jiangsu, on 18 August 1930. His mother died when he was 8, and he was raised by his paternal grandmother. He secondary studied at Jiangsu Provincial Liyang High School (). In 1950, he was admitted to
Tsinghua University, where he majored in
biology. A year later, he was sent to study at the
University of Leningrad (now Saint Petersburg State University) on government scholarships. Zhai returned to China in 1956 and that same year became a professor at the Department of Biology,
Peking University. In 1959, he pursued advanced studies at the Institute of Biophysics of the
Soviet Academy of Sciences. He returned to China in 1961 and continued to teach at Peking University. In 1969, during the
Cultural Revolution, he was sent to the
May Seventh Cadre Schools to do farm work in the suburb of
Nanchang,
Jiangxi, and returned to Peking University in 1973. He was a visiting scholar at
Massachusetts Institute of Technology from 1985 to 1986, studying nuclear skeleton and its relationship with gene expression under the supervision of S. Penman. Zhai died in
Beijing on 10 February 2023, at the age of 92. ==Honours and awards==