Online education provides students with more learning opportunities, but the depth and breadth of students' participation in online learning needs to be improved. Using Structural Equation Modeling (SEM), the article examines the impact of student participation in an online learning environment on academic retention. The experimental results show that when the student participation rate reaches 97.7%, academic retention can reach 99.3%. From this we can draw the following conclusions: (1) In a fully online learning environment, the higher the degree of student engagement is, the higher the academic retention is; (2) in a fully online learning environment, students' self-efficacy is positively correlated with academic retention; (3) in a fully online learning environment, teachers have a relatively small effect on student engagement and academic retention; (4) the higher the degree of teacher engagement is, the greater its impact on student academic retention is. The findings of the article can help schools develop more effective strategies to improve student engagement and academic retention, thereby improving the effectiveness of online learning for students.