Procrastination is an unnecessary behavior which prohibits initiating and completing the given tasks. The purpose of this study was to examine the two subtypes of academic procrastination, academic initiation-procrastination(AIP) and academic completion- procrastination(ACP), and investigate the psychological mediating factors AIP and ACP. A series of empirical studies were conducted to assess (1) the possible mediating role of task avoidance/sensation seeking(TA/SS) in the relationship between impulsiveness and AIP, and (2) the mediation effect of the feeling of incompleteness in the relationship between perfectionism and ACP. In this study, 234 undergraduate students completed several surveys - the Academic Initiation- Completion Procrastination Scale(AICPS), Multi-dimensional Perfectionism Scale(MPS-F), Barratt Impulsiveness Scale(BIS), task avoidance/sensation seeking(TA/SS) and incompleteness scale - and the relationships among the variables were analyzed. The results revealed that TA/SS partially mediated the relationship between impulsiveness and AIP. Also, Incompleteness fully mediated the relationship between perfectionism and ACP. The findings of this study can provide additional explanation of psychological mechanism in academic initiation- and completion-procrastination. The limitations and clinical implications of this study and suggestions for further study are discussed.