With 118 non-English major undergraduates as the participants and through an interventional experiment,this study investigated the effectiveness of online university English textbook use based on the ARCS(attention,relevance,confidence,satisfaction)motivation theory.The findings revealed that the ARCS motivational regulation strategies effectively enhanced the students'motivation for textbook use,learning experience,and academic achievement,albeit with varying degrees of influence on the four dimensions of motivation.The study elucidated the relationship between motivational regulation and textbook use in online teaching,providing insights for instructors to optimize instructional design and for students to improve learning effectiveness.