Liu Jun (Chinese: 劉鈞) (926–968), originally Liu Chengjun (Chinese: 劉承鈞), also known by his temple name as the Emperor Ruizong of Northern Han (北漢睿宗), was the second emperor of the Shatuo-led Northern Han dynasty of China.
His capital was at Taiyuan, Shanxi Province.
He was the second son of the Northern Han founder Liu Chong (Emperor Shizu).
In 951, after the death of his brother Liu Yun, he became the heir of his father.