This thesis mainly explores the motivation of Chinese college students who participated in the “Challenge Cup”, a national competition for extracurricular academic and technological achievements in Chinese universities. Based on the relevant motivation theories, the researcher proposed a conceptual causal model for different motivational variables. The SEM (Structural Equation Modeling) method was adopted in order to testify the hypothetical model. The data fits the model very well, which indicates that interest and self-efficacy can significantly predict the effort.Valenceas an important mediator plays indirect effect on effort. Mastery orientation, rather than performance orientation, has significant effect on effort. Descriptive statistical results show that mastery orientation has the highest mean (M=4.30), while the lowest mean is performance orientation (M=3.57). The overall motivations of college students who got high achievements in this competition are high. The general strength of motivation is comprehensively determined by the systematic functions of all variables.