Electro Discharge Machining (EDM) is an emerging technology in the field of machining to fabricate very complex micro products. Wire EDM is a very complex process involving the different process parameters. The experiments are often time consuming and costly. It is used to manufacture geometrically intricate shapes with great accuracy and good surface finish that are difficult to machine with the help of conventional machining processes,but recent development in material have become a difficult task for WEDM process to be used for machining alternative in future,so there is need to make continuous improvement in current WEDM process to increase their productivity and efficiency in WEDM have directly contributed to increased cutting speed and dimensional accuracy. This paper reviews the various notable works in the field of WEDM and emphasis is made on optimization of machining parameters.