Purpose: This study connects self-determination theory (Deci & Ryan, 1985, 1991), leisure constraints (Crawford & Godbey, 1987), and flow theory (Csikszentmihalyi, 1975) as its basis, while integrating related literature to construct the relational model between the motivation, discouragement and flow of college tennis athletes. The model includes the three latent variables of motivation for participation, discouragement factors, and flow experience as well as 12 observed indicators. Methods: This study uses Structural Equation Modeling (SEM) as its method, collecting observation data to verify the goodness of fit of the relational model in question. The research subjects include 428 local students competing in college tournaments in 2014, the research tools includes three scales, one each for motivation for participation, discouragement factors, and flow experience, as well as confirmatory factor analysis and convergent validity, discriminant validity, composite reliability and average variance, which was then combined into the relational model. Results: The study results show good composite reliability and validity. As for the relational model showing the motivation of participation for college tennis athletes having a positive effect on flow experience (Path coefficient of .48), the discouragement factors had a negative effect on participation of college tennis athletes (Path coefficient of -.88). It followed that discouragement factors had a negative effect on flow experience (Path coefficient of -.52). Conclusion: The study results indicate the relational model between the motivation for participation, discouragement and flow of college tennis athletes fit the observed data. In addition, the results are consistent with the research results of recent related studies. Lastly, a discussion of the theoretical meaning of the study results is presented, and suggestions for future research are provided.