Following the formal establishment of the Democratic People's Republic of Korea, he was the first Minister of Interior in the North Korean Cabinet.
After the Sino-Japanese War, he worked as an on-site in the medical examination area (晉察冀 邊區, local government of China).
He served as an instructor at the Coastal Military Administration University, and in July of the same year, he was appointed deputy commander of the Korea Medical School and launched an anti-Japanese struggle.
In 1951, Kim Il Sung dismissed Mu Chong the most powerful figure in the Yan'an faction, the deputy minister of the Ministry of National Defense and the artillery commander of the Korean People's Army, on the grounds of "lost Pyongyang" and "weak combat".
Pak Il-u who was the internal affairs minister considered to be a personal representative of Mao Zedong, was replaced by Choe Yong-gon in the post of deputy political commissar of the Joint Command of the Chinese and Korean Army in February 1953.