The previous scholars of Yi grammar used to imitate Chinese grammar in studying Yi grammar. They took it for granted that the Chinese‘不’means 'ap' in Yi and the Yi 'ap' means‘不’in Chinese, so the usages of the Chinese‘不’and the Yi 'ap' were thought to be absolutely the same. Because‘不’is an adverb in Chinese, so the 'ap' of Yi must be an adverb too! But through camparison and analysis, the meaning, the part of speech and the usages of Chinese‘不’and Yi 'ap' have more differences than similarities.