Impression updating, as a dynamic process being focused on recently, makes it accessible to the change in first impression and meticulously affect interpersonal relationship, social attitudes, decision-making, and personal judgment. This article gives a comprehensive review of literature on theoretical process of impression updating in terms of discrepancies between explicit and implicit cognitive process, impacts of essential information elements on impression updating and its neural basis. Five illuminating findings were obtained: (1) Current theories tried explaining differences between implicit and explicit impression updating from the perspectives of multiple memory system and information processing. Dual-process model suggests that implicit and explicit evaluations are generated by two different psychological processes. Single-process model holds that implicit evaluation is the product of multiple interacting systems, each of which has its own characteristics of acquisition and disappearance. On the whole, the theories explaining contrasts between implicit and explicit impression updating remain to be uncovered in the future. (2) The existence of implicit impression updating is volatile, with essential information elements playing an important role in the process of implicit impression updating. However, how does information diagnosis in terms of different intensity, credibility, reinterpretation and attribution, affect processing rate, persistence and stability of implicit impression updating are still unclear. Besides, expected consistency with stereotype may also impact implicit impression updating. (3) Implicit impression updating varies in perceived dimension and content. As for perceived dimension, morality outweighs competence and warmth in impression updating. Considering content, salience and valence of cues can cause impression updating bias. Emotional and motivational factors such as social distance, perceiver group identity and relationship maintenance also have an impact on implicit impression updating. However, more systematic and comprehensive theories are needed to explain conflicts among current findings. (4) It is future trend to study implicit impression updating using various novel paradigms, such as exploring the neural basis of impression updating in combination with cognitive neuroscience technology, and utilizing dynamic measures of impression, such as reinforcement learning task paradigm, with the help of computer technology. (5) It is necessary to give cross-culture studies on the explicit and implicit impression updating under individual and group levels, and extend antecedents and aftereffects of impression updating, so as to strengthen the cross-cultural comparative research on impression updating.