In the imperial examinations in the Tang Dynasty, fellow scholars called each other the same year, called examiners masters, teachers or benefactors, and called themselves students. In this way, the new Jinshi and the examiner have established a very special teacher-student relationship. They may form a political party for self-interest and establish and cultivate their own power, which is very unfavorable to the centralized rule of the emperor, as evidenced by the struggle with Li in the late Tang Dynasty.

In the Northern Song Dynasty, in view of this, Song Taizu and Zhao Kuangyin asked all candidates admitted to the Ministry of Rites to have a second interview in front of the temple, and the emperor personally determined the final admission ranking, so the imperial examination system evolved from a two-level examination system to a three-level examination system.

According to Ye Mengde's "Misty Rain in Shilin" (Volume 8), in the sixth year of Kaibao in Song Taizu (AD 973), Liu Yun, a bachelor of Hanlin, presided over the provincial examination and admitted 38 candidates. When Zhao Kuangyin summoned these candidates, he found that two candidates were eliminated because of poor materials, and one of them named Wu Jichuan happened to be Liu Yun's hometown, which aroused Mao's suspicion. At that time, some of the last candidates just drummed and accused Liu Yun of corruption, hoping for a second interview. Therefore, Mao ordered 195 candidates to be selected from the last batch of candidates and take the palace exam together with 38 people who had already been admitted. Results Among the 38 people who were admitted, 10 was unsuccessful. Liu Yun was therefore demoted, and the imperial examination became the highest level of the imperial examination, which lasted until the Qing Dynasty.

In fact, the imperial examination existed as early as Wu Zetian's time, but it was intermittent in the Tang Dynasty and did not form a system. Therefore, the imperial examination in the Tang Dynasty was actually a two-level examination system of the state government and the provincial examination of the Ministry of Rites.