Episodic memory has been defined as the memory for personal experiences in time and place. For the purpose that whether consciousness is a necessary condition of episodic memory formation, the current research discussed that episodic memory could be formed under the unconscious condition. This survey opens a new window towards understanding the human’s episodic memory. 　　We first introduced the episodic memory system proposed by Tulving. According to the view of Tulving, episodic memory is a recently evolved in the phylogenetically history, late developing and early deteriorating in the development history of the individual, past-oriented memory system, and probably unique to humans. Later, he pointed out that episodic memory had three characteristics such as auto-noetic awareness, self, and sense of subjective time, which referred to a person’s awareness of his existence and identity in subjective time extending from the personal past through the present to the future and allowed us to be aware of the subjective time in which events happened. 　　Then, this study discussed that episodic memory could be formed under the unconscious condition. In these parts, we described a wide range of unconscious episodic memory in visual and verbal processing, amnesia patients, infant and animals research. In the respect of static visual and verbal, the previous study indicated that rapid encoding and flexible representation could be formed in unconscious condition, and the brain areas which rapid encoding and flexible representation depended on could be adjusted by the unconscious process. In the perspective of dynamic visual, the early study concluded that there was a motor system in addition to the use of verbal mediation and a visual-sensory modality in the processing of episodic memory and the encoding of motor tasks was nonstrategic in some respects. The research in amnesia patients indicated that amnesia patients with hippocampus damaged not only missed the explicit declarative memory, but also lose the unconscious memory needed rapid encoding and flexible representation, which also belongs to the component of episodic memory. According to the view of Tulving, the young infants and animals should not have the ability to form episodic memory. However, recent studies demonstrated that both young infants and animals possess some of the properties of episodic memory. The above discussion indicated that episodic memory could be formed under the unconscious condition. 　　Finally, based on the analysis of the development of episodic memory which exhibited the natural and social properties in the evolution history, the current research manifested that the advanced, conscious episodic memory in human being was generated in leaps, which relied on the foundation of low and unconscious episodic memory. Accordingly, the episodic memory in human beings had the low and unconscious attributes and showed qualitatively distinct from the unconscious episodic memory in animals. The future research should not only pay attention to the natural properties of episodic memory, but also focus on its social attributes, so as to explore a new model for episodic memory research which integrated from the low processing to the advanced processing.