Taiwan began to implement a new high school syllabus nationwide, in 2019. The Ministry of Education has also established a high school student Academic Portfolio System (APS) to collect the learning process of high school students for future university admissions references. However, during this period, high school students and their parents had many opinions on the implementation of the new system. There were even groups of students protesting. The main purpose of this research is to explore the factors that affect the system usage intentions of high school students. Based on the theory of reasoned action (TRA) and the technology acceptance model (TAM), this research established a research model. The research variables include system interface design, usefulness, ease of use, attitude, subjective norms, and usage intentions. A total of 712 questionnaires were collected from high school students in northern Taiwan. Data analysis is carried out in three stages: descriptive analysis, measurement model verification, and structural equation modeling. The results of the study found that system interface design has a significant impact on the perceived ease of use. Factors such as ease of use, usefulness, attitude, and subjective norms also have a significant positive impact on usage intention; ease of use and usefulness positively affect attitudes toward using. Finally, according to the results, some practical implications were proposed for implementation references from the perspectives of education authority, high schools, teachers, and students.