Cui Jia-yan, styled Xi Fan, known as Zi Xu Zhenren, was one of the renowned physicians of Xu River (now known as Fu River, which flows through the eastern part of Jiangxi Province). He was from Nankang, Jiangxi Province (during the Southern Song Dynasty, Nankang Prefecture included areas such as Xingzi, Yongxiu, and Duchang, with its administrative center in present-day Xingzi County). He was a Taoist during the Chunxi period (1174-1189) of the Song Dynasty. Some sources suggest he was a Taoist during the reign of Emperor Huizong of Song (1101-1125), living in the 12th century and enjoying a lifespan of over seventy years.

Cui was well-versed in medical arts, particularly skilled in the study of pulse diagnosis, and authored Cui's Maijue (also known as Cuizhenren Maijue or Zixu Maijue). Additionally, he annotated the pulse study work Yuhan Jing by the late Tang and Five Dynasties period Taoist Du Guangting.

Cui also authored a one-volume work titled Siyuan Lun, which has been lost.