Stigma in essence is a negative stereotype. It is a devalued and insulted label which is imposed on some individuals or groups by the public. Stigma has profound effects on its targets. This article reviews the stigma-related literatures in three aspects. First, some important definitions of the stigma are introduced. Then the psychological effects of stigma are interpreted, including the function of stigmatizing others, the influences of stigma on the stigmatized individuals and the public attitudes and reactions to stigmas. Third, researches in two main areas of stigma are reviewed: 1. studies on discrimination of stigmas, and 2. studies of concealable stigma, e.g. psychological process and emotions of concealing stigma, implications of disclosing stigma etc. Finally, prospects of stigma studies in the future are recommended: studies of concealable stigmas, implicit social cognition and intervention to eliminate the negative influences of stigma