The present longitudinal study investigated, on one hand, the mediating effect of achievement emotions on academic self-concepts/ academic achievement relations; on other hand, the reciprocal causation effects among the study variables were examined. Across two consecutive university semesters, a convenience sample of 257 university undergraduates from several universities in Hong Kong participated the survey investigation under self-report basis. The result of reliability analysis and Confirmatory Factor Analysis (CFA) were revealed as satisfactory. In line with the proposed hypotheses, the outcomes from Path analyses and Structural Equation Modeling (SEM) indicated the existence of significant direct (academic self-concepts to academic achievement) and indirect effect among the constructs within same time period and across time periods. More specifically, the academic self-concepts (Verbal, Problem Solving and Academic) demonstrated negative predictive effects on negative achievement emotions (Anger, Shame, Hopelessness and Boredom), whereas negative achievement emotions, in a small extent, negatively predicted the academic outcomes. As a result, the direct effect between academic self-concepts and academic achievement was found to be weakened but significant, also partially mediated by the negative achievement emotions. Consistent with another hypothesis, strong reciprocal causation relations between prior and subsequent constructs were observed. Prior academic self-concepts was confirmed to be significantly influential to subsequent academic self-concepts, whereas prior negative achievement emotions negatively predicted and positively associated to academic self-concepts and negative achievement emotions in the following time period. Positive feedback loop was said to be formed under such circumstances and intensifying its effects over time as well. Discussion centers on the new findings about the two control-related beliefs on individuals going through stage of young adulthood. Education implications and directions for future studies are moreover presented.