This study explored the relations among peer victimization (i.e., physical, relational, and cyberbullying victimization), learning flow, and academic achievement among elementary school students, using a seven-wave longitudinal design across four consecutive semesters. Participants were 1,440 students from Grades 3 and 4 in China (M[subscript age] = 9.91 years, 52.4% male). Measures of peer victimization and learning flow were completed in the middle of every semester, from the second to fourth semesters. Academic achievement was measured via students' final exam scores in Chinese, Math, and English at the end of each semester. The results indicated that: (a) relational victimization, but not physical and cyberbullying victimization, directly predicted subsequent lower academic achievement; in the reverse path, lower academic achievement predicted all three types of subsequent peer victimization; (b) learning flow directly predicted academic achievement and vice versa; and (c) learning flow mediated the relations between the three types of peer victimization and lower academic achievement. The findings suggested that educational experiences are needed that both protect elementary school students from relational victimization and facilitate learning flow to promote students' academic achievement.