Abstract: With the development of massive storage system and its application in complex environments, there is a big challenge in the reliability of storage system. Erasure code is drawing more and more attention since it is the main technology for fault tolerance in storage systems. In this paper, we firstly introduce the current-status of some typical and popular erasure codes, then make careful comparison and analysis on current erasure codes with the important metrics that are used to evaluate them. Afterwards, we point out some shortages and improvement suggestions on fault tolerance, requirements for the number of disks, storage efficiency, encoding efficiency, updating efficiency and decoding efficiency for different erasure codes. What’ more, we discuss the different requirements on erasure code in disk array systems, P2P systems, distributed storage systems and archival storage systems. Finally, we indicate the unresolved problems in erasure code and their future trends. From the analysis, we found a lot of drawbacks on fault tolerance, storage efficiency and computation efficiency (including encoding efficiency, updating efficiency and decoding efficiency) for different erasure codes. It is an issue worthy of further study in a long period to make a balance on these factors and create new erasure code with higher fault tolerance, greater storage efficiency, and faster computation efficiency.