The purpose of this study was to explore optimal flow experiences of students in an online learning environment for the Chinese language. Based on prior studies, the study adapted the framework of flow theory which consists of 9 sub-factors: challenge, awareness, goal-oriented, feedback, concentration, control, self-consciousness, sense of time, and intrinsic rewarding. The study showed that students had flow experiences in an online learning environment for the Chinese language. The findings by correlation analysis and hierarchical regression analysis indicated that all the sub-factors of the flow construct are positively co-related to overall learning satisfaction as well as students" perceptions on online learning processes and their task accomplishments. In particular, one flow sub-factor is called "control" was identified to have more predictive power to explain perceived satisfaction for online foreign language learning, which might eventually influence students" actual learning outcomes.