South Korea (SK), North Korea (NK), and ethnic Koreans in China (KC) commonly have language unity in grammar subject and textbooks. KC represents a neutral view in North Korea's language unit development method, unit construction system, and grammar contents. Unit arrangement methods of grammar textbook are systemic in SK and KC while those of NK are composed of a simple enumeration. Observing units individually, SK has a basic unit construction system in textbooks such as 'introduction-development-arrangement'. Meanwhile, NK and KC show the difference from SK by only presenting 'explanation-exercise' system. SK emphasizes the sentence unit the most; however, NK and KC put significance on the word unit. In addition, SK and NK stress language norms in grammar textbooks, but KC does not mention the subject. NK and KC discuss a 'literary style' in grammar textbooks while SK's textbooks lack the information. With the grammar content's aspects, NK and KC have respectively named the grammatical particle and ending as 'Cheeonto'(체언토) and 'Yongeonto'(용언토). The grammatical particle and ending show their non-substantive characteristic. SK and KC view the passive and causative suffix as suffix, but NK differently account them as 'tto'(토).