North Korea holds the first full congress of the ruling party in 36 years.
North Korean President, Mr Kim Jong-un is expected to reassert his nuclear ambitions, amid speculation he will soon conduct a fifth nuclear test.
Reports said foreign media have been invited but are not allowed inside the venue.
The capital was spruced up ahead of the event and citizens’ layed flowers in central squares as it got under way.
The streets are lined with National and Workers’ Party flags with banners that read “Great comrades Kim Il-sung and Kim Jong-il will always be with us” and “Defend the headquarters of the Korean revolution at the cost of the our lives”.
It is the seventh meeting of North Korea’s Worker’s Party and the first since 1980.