Purposes: Flow has been identified as a key construct in the field of positive psychology. The study aimed to explore the relationship between flow experience, intrinsic/extrinsic motivation, math anxiety and math performance in high school students. Methods: 296 high school students (163 male, 133 female) were recruited to complete the Inventory of Flow at Examinations (developed for the study), Mathematics Motivation Scale, and Mathematics Anxiety Scale. All instruments were administrated immediately after students have finished their monthly math exams. Results: Path analysis were utilized and revealed four significant paths: intrinsic motivation→flow experience→math performance, math anxiety→flow experience→math performance, extrinsic motivation→flow experience→math performance, extrinsic motivation→math performance. Conclusions: Both intrinsic motivation and math anxiety have no significant direct effects on math performance; only through the mediation of flow experience, intrinsic motivation and math anxiety would exhibit influence on math performance.