Objectives The purpose of this study is to obtain educational implications by examining the patterns of nasalization errors (correct and incorrect answers) that appear in each environment among Vietnamese Korean language learners. Methods In order to proceed with this discussion, we first reviewed previous research and theoretical background, and then established standards to analyze the nasalization error rate by environment. After that, from January 30, 2023 to January 30, 2024, in Korea, 19 to 30-year-olds After a basic survey, 15 Vietnamese Korean language learners (5 men and 10 women each) met 1:1 via Zoom and were asked to utter pre-prepared words related to nasal pronunciation. Then, by determining whether the answer was incorrect or correct, more detailed error types and their characteristics according to the overall results and characteristics of each environment were extracted. Results As a result of the analysis, through a review of previous research related to contrastive linguistics, it was possible to understand the fundamental cause of nasalization through differences in syllable structure between the two languages, and through a basic survey, despite the high demand for nasalization education, there was no awareness due to lack of educational experience. I could see that it was lacking. In addition, the results of error patterns by environment showed that the highest rate was in the case of ‘nasalization after adding ‘ㄴ’ or ‘nasalization after consonant group simplification.’ It was found that this was caused by a lack of awareness of nasalization by environment among the nasalization rules of Korean, the standard language. In addition, the higher error rate at ‘word boundaries’ rather than ‘word interior’ showed that nasalization education should be done ‘by phrase’. Lastly, as a result of examining error patterns by region, grade, and gender in an environment that previously showed a high error rate, all grades showed similar difficulties in pronunciation of bar consonants, but by region, it was more common in the south than in the north and central regions, and by gender, more than in women. A high error rate was observed in men. Conclusions In this way, this study identified the actual status of nasalization errors (total error rate by environment and error rate by word interior/boundary) of Vietnamese learners in more diverse environments and, unlike existing previous studies, provided basic data and implications for preparing educational measures. It was a meaningful study in that it was able to obtain results.