The most important function was to promote independent peaceful reunification policies, which were the core of the Yushin Constitution, and indirect presidential elections during the 4th Republic From August 1973, the NCU was decided as National Assembly.

The National Assembly was composed of delegates directly elected by the people from each district across the country, and the delegates of the National Assembly for Unification were unofficially called Tongdae.

According to Chapter 3 of the Yushin Constitution of the Republic of Korea at the time, the National Assembly for Reunification was the top institution of the state and a sovereignly entrusted institution, a place where the people's consensus to promote the peaceful unification of the country was gathered.

In effect, this institution, which served as the flag bearer of President Park Chung Hee, took on the role of formally electing the successor presidents Choi Kyu-ha and Chun Doo-hwan after he was assassinated on October 26, 1979.

After that, the agency in charge of the Presidential Election System was replaced by the Presidential Electoral College, and its role as an organization related to the secretariat, personnel composition, and unification under the direct control of the President continued through the 'Peace and Unification Policy Advisory Council' and then the Democratic and Peaceful Unification Advisory Council.