Balhae(698~926) was the ancient state which opened the Nambuk-guk period with the Unified Silla. But Balhae architecture began to included in the history of Korean architecture only about 15 years ago, such as the books written by Yun Jang-seop or Ju Nam-cheol. I discussed four issues related to Balhae architecture in this paper. First, I criticized the excavation report of 24 stones remains at Jiangdong in Duhua city, and I asserted the ondol site belonged to different period. Second, I also interpreted that the building found on the tombs no.13 and no.14, in the Longhai burial area in Helong city must be a wooden stupa. Third, Balhae played some important roles in the history of ondol. It developed Koguryeo ondol in terms of structure, gave an opportunity to the ruling class to adopt ondol for the first time, and passed the heating system down to the Jurchen, the ancestor of the modern Manchurian. Fourth, the Russian-Korean joint research team excavated seven building sites in Koksharovka 1 fortress from Russian territory these four years, and it is reasonable to assume the fortress was the center of Anbyeon-bu, one of 15 local government districts in Balhae. I guess this buildings were the royal shrine built by resisters after the fall of Balhae, and the vessel stands found there must be used for ancestral memorial ceremony inside them.