The purpose of the current study was to analyze the combined effects of both personality traits and learning environment on university student imagination of educational technology major, and to test the mediating effect resulted from the variable of human aggregate. The results of this study supported that imaginative capabilities were consisted of ten characteristics, and the influences of learning environment were composed of five indicators. The hypothesis of this study-that human aggregate plays a mediator in imagination-stimulation-was partially supported. The structural model also showed that most personality traits had direct effects on imagination, while most environmental variables had indirect effects. Our results highlighted the importance of understanding both the individual personality and learning environment for the educational technology students, so that optimal levels of reproductive imagination and creative imagination could ultimately be elicited.