It is not known when Cui Hao was born. He was the oldest son of the ethnic Han Cui Hong (崔宏), a high-level official under Emperor Daowu, who carried the title of Marquess of Baima. In Cui Hao's youth, he was said to have studied a broad number of books, but was particularly known for his literary abilities, as well as his astrological prophecies. The first historical reference to Cui Hao was in 409, when he was a low-level official in Emperor Daowu's administration. At that time, Emperor Daowu was often violent and arbitrary in his actions, because of poisoning from pills he received from alchemists, and the imperial officials often found excuses to stay away from him lest that they be stricken by his anger. However, Cui Hong and Cui Hao were described of having served Emperor Daowu diligently despite this, and they were among the few officials who never received any punishment from him.