The title of the thesis is informative and economical, and is an important part of academic achievements such as academic papers and dissertations. Title writing has prescriptive requirements and standards in many aspects such as vocabulary, grammar and rhetoric. However, the high frequency and complexity in the usage of English definite article make it often misused in the title writing of bachelor’s degree thesis for English majors. Through investigating and analyzing the misuse of the definite article in the titles of bachelor’s thesis by English majors over the past five years (2020–2024), this study seeks to categorize and summarize the types of misuse and explore the underlying causes of such errors, thereby providing reference insights for the acquisition of the English definite article.