Civil Associations Act Article 47

The national administrative region shall be the organizational area of a party, and no regional party may be founded. However, branches may be established.
中文原文 人民團體法第47條
政黨以全國行政區域為其組織區域,不得成立區域性政黨。
但得設分支機構。

English translation for reference only; the Chinese text prevails. Not legal advice.