This study examines the differences in the criteria for analyzing colloquiality in Korean and Chinese at various levels, including phonological-morphological, lexical, syntactic, and discourse-pragmatic dimensions, and considers how these differences negatively affect Chinese learners’ use of the spoken and written distinction in Korean. The results show that at the phonological-morphological level, Korean can use morphological variation as a criterion for analyzing spontaneity, but this does not apply to Chinese. At the lexical macro level, Korean tends to be colloquial and written depending on its etymology, while Chinese is colloquial and written depending on the number of Chinese characters. At the micro level, the differences were analyzed through the terminological endings of Korean and Chinese. Syntactically, Korean is characterized by the omission of the accusative case and monomorphemic negation, whereas Chinese does not show a colloquial-grammatical distinction in word order and infinitive morphology. At the discourse-pragmatic level, Korean is characterized by strong ‘audience-conscious expressions’ depending on the presence or absence of an audience, whereas Chinese does not have such a criterion for analyzing colloquiality due to its lack of elevation. Based on the results of the above analysis, pedagogical implications were presented to improve Chinese learners’ colloquialisms in academic writing.