This study explores the interdisciplinarity measurement in grammar education research based on Latent Dirichlet Allocation (LDA) topic modeling. To this end, the theoretical and methodological issues of interdisciplinarity measurement were reviewed. Then, a corpus was built with research articles in the field of grammar education, and the topic modeling of LDA was carried out. Using the topic modeling results, an interdisciplinarity index based on Sterling’s diversity index was calculated, and the value was standardized. By comparing the interdisciplinarity index values between corpora of grammar education studies in this way, it was confirmed that interdisciplinarity in grammar education research could be measured through topic modeling. This study is meaningful in that it identifies various issues encountered when measuring interdisciplinarity in grammar education research using topic modeling and Stirling’s index, and provides a specific method for each issue.