He was from the "Lesser Branch" of the prominent Cui clan of Qinghe (清河, in modern Xingtai, Hebei), and his ancestors originally claimed ancestry from the ruling house of the Spring and Autumn period state Qi.
[5] After Cui himself passed the imperial examinations in 849 (during the reign of Emperor Xuānzong), he served on the staffs of several regional governors.
[2][7] In 874, Cui was recalled from Hedong to serve as the deputy minister of civil service affairs (吏部侍郎, Libu Shilang) and the director of the salt and iron monopolies.
[2] Later in the year, when he was referred to as deputy minister of defense (兵部侍郎, Bingbu Shilang) and director of finances, he was made Zhongshu Shilang (中書侍郎), the deputy head of the legislative bureau, and given the designation Tong Zhongshu Menxia Pingzhangshi (同中書門下平章事), making him a chancellor de facto.
[2] When he became chancellor, however, his mother, fearful that he would punish his cousin Wang Ning, who was then the deputy minister of defense, commented to her maid servant within Cui's earshot, "Make some new socks and shoes for me.
[3] In 876, because of illness, Cui was removed from his chancellor position and made a senior advisor to the Crown Prince.