The scope of this study was limited to the first spelling question out of 30 Vietnamese questions of each SAT from 2014 to 2023. To analyze the difficulty of the spelling questions, we analyzed the format of the questions focusing on the questions sentence and examined how many times the vocabulary in the questions was exposed, starting from which page of the EBS CSAT Special Lecture, which is the main exam book in reality. In addition, as another criterion for measuring difficulty, we used the Vietnamese vocabulary classification presented in the standard curriculum developed as part of the Critical foreign Languages Education Promotion to see what level the vocabulary on the question corresponds to. To summarize the characteristics of the four periods divided based on the questions sentence, the difficulty level of the spelling questions was inconsistent over the past 10 years and became difficult in the second period, but through the third and fourth periods, the level of completion increased and the difficulty level found its appropriate level.