Born in Kaechon City, South Phyongan Province, Jang started his career at the Mass Gymnastics Production Company in 1976 after graduating from Kim Hyong Jik University of Education.

In his twenties he successfully carried out the production of a section of mass gymnastic display "Song of Korea", a scene performed by at least 1,000 gymnasts. His admirable talent and organizing ability drew deep attention of the mass gymnastics production world.

Since 1981, he had acted as the general conductor of the background, one of the three main components of mass gymnastics. In the course of producing and conducting the backgrounds in several mass gymnastic displays, he further improved his construction ability, which is to shape vast space and huge personnel into an organic one, and got senses of a mass gymnastics producer.

Typical of the works directed by him is the mass gymnastic display "Do Prosper, My Motherland", created to celebrate the 60th anniversary of the DPRK.

During his life of 36 years as a creator Jang produced tens of mass gymnastic displays and spread the DPRK's experience and technique of mass gymnastics production among other countries.

He was awarded Kim Il Sung Prize in 2006 and the title of People's Athlete in 2001 for his signal contribution to the development of the nation's mass gymnastics.

Jang Un San, deputy head of the Mass Gymnastics Production Company, is now directing the production of grand gymnastic and artistic performance "Arirang".