Authorities in Vietnam say the purpose of the meeting is to "deepen and develop bilateral relations between Vietnam and the Holy See," whilst the Vatican says it's to "strengthen and develop bilateral relations between Vietnam and the Holy See."
Discussions to create better links between the two were ended abruptly in 1975 after the war.
Catholics are faced with serious constraints on religious freedom and it's thought the Vatican will push for more respect from government.
Around 8 per cent of Vietnam's population are Catholic.
At the sixth Asian Youth Day Pope Francis said Asian governments should not be concerned by the Vatican because: "Christians don't come as conquerors, they don't come to take away our identity: they bring us their own, but they want to walk with us".
"The Church is called to be versatile through dialogue and openness to all".