Rain Classroom, a popular online learning platform in China, has been developed to face the constant innovations of teaching pedagogy. However, few studies have attempted to understand its users’ sustained attention under the guidance of the unified theory of acceptance and use of technology (UTAUT). Based on the authentic relationships between constructs of the UTAUT model, this study tries to determine the factors that influence users’ sustained attention to Rain Classroom by replacing the two dependent constructs, use behavior and behavioral intention with sustained attention and self-efficacy. There were 421 students from a public university in China involved in this study. By using the data collected from an online questionnaire, the current research tested five hypotheses. The results were consistent with the relationships in the original UTAUT model except for effort expectancy. The theoretical and practical implications of this research were also discussed.