From knowledge dynamics perspective, knowledge management mainly includes organizational learning, organizational memory and organizational forgetting. In the context of change and cross-culture, more and more scholars pay attention to knowledge management from the perspective of knowledge forgetting, particularly in active forgetting obsolete knowledge. That is unlearning. According to the past literatures, this paper firstly gives a summary of the concept and connotation of unlearning. At the same time, we talk about the evolving process of unlearning and discuss the difference and connection between organizational unlearning and learning. Then we analyze the mechanisms of unlearning. Based on the types of knowledge, we discuss the different levels of unlearning between individuals and organizations. Meanwhile, we also discuss the process mechanism of unlearning, which includes the behavior process and the cognitive process. Finally, we discuss about future research directions and issues. One the one hand, we should study factors that hinder organizational unlearning more and establish corresponding mechanisms to overcome these negative factors. On the other hand, we should pay more attention to the interactions between organizational unlearning and unlearning and keep balance between them.