In clinical work, it is observed that keloid has significantly different characteristics from other types of scar such as hypertrophic scar. The growth of keloid usually exceeds the margin of original wound and continuously invades the surrounding skin, and keloid has a certain recurrence rate after various treatment measures such as surgery and glucocorticoid injection, etc. The above phenomenon suggests that keloid has certain tumor characteristics, and we cannot judge keloid from the perspective of scar alone. This article attempts to re-describe the pathogenesis of keloid from the perspective of tumor and summarizes the tumor characteristics of keloid from self-sufficiency of growth signal, avoidance of apoptosis, and abnormal angiogenesis, etc.