The purposes of this paper are to compare orthography and phonetic rules of Sai-sori (SA) within the language norms between South and North Korea, and to seek the unified orthography and phonetic rules of SA. Because the two Koreas’ language norms are historically based on ‘Hangeul Orthography Unification’(1933), similarities on the orthography of SA are found. The basic principles are rooted upon the formalized orthography theory, and both nations recognize the phonetic rules of SA. Also, ‘ㄷ’ or [t] and ‘ㄴ’ or [n] sounds are admitted to have a common as specified SAs as well as ‘ㅂ’ or [b] and ‘ㅎ’ or [h] as historical SAs. However, a few differences are also detected. South Korea uses Saisios (‘ㅅ’) while North Korea does not. In addition, South Korea marks the historical ‘ㅎ’ or [h] as they utilize the words, ‘수캐’ and ‘암퇘지’. On the other hand, North Korea dismisses the usages of ‘ㅎ’ as they mark the words, ‘수개’ and ‘암돼지’. South Korea only applies ‘ㅅ’ in 6 Chinese words, but North Korea’s language does not contain a single usage of ‘ㅅ’. I suggest that Saisios can be omitted in the future unified Korea. It means that the formalism idea is sustained and preserved well. It would become simpler to indicate any SA expressions in dictionaries with phonetic marks. The rule could be applied to the native tongue or Chinese Korean words.