With the development of semiconductor technology and CMOS scaling, the size of on-chip cache memory is gradually increasing in modern processor design. The density of traditional static RAM (SRAM) has been close to the limit. Moreover, SRAM consumes a large amount of leakage power which severely affects system performance. Therefore, how to design efficient on-chip storage architecture has become more and more challenging. To address these issues, researchers have discussed a large number of emerging non-volatile memory (NVM) technologies which have shown attractive features, such as non-volatile, low leakage power and high density. In order to explore cache optimization approaches based on emerging non-volatile memory including spin-transfer torque RAM (STT-RAM), phase change memory (PCM), resistive RAM (RRAM) and domain-wall memory (DWM), this paper surveys the property of non-volatile memory compared with traditional memory devices. Then, the advantages, disadvantages and feasibility of architecting caches are discussed. To highlight their differences and similarities, a detailed analysis is then conducted to classify and summarize the cache optimization approaches and policies. These key technologies are trying to solve the high write power, limited write endurance and long write latency of emerging non-volatile memory. Finally, the potential research prospect of emerging non-volatile memory in future storage architecture is discussed.