In the Spark Erosion machining process, the electrical energy in the inter-electrode gap gets converted into thermal energy. Whatever thermal energy generated in inter electrode gap gets distributed among anode, cathode and the dielectric fluid. The workpiece in spark erosion process is kept as anode and the fraction of the total energy which is going to the anode (workpiece) should be maximum. As this thermal energy is responsible for the melting of material on the workpiece. This fraction of energy is the important parameter used to predict the effective use of total heat energy generated between tool and workpiece. The fraction of energy that is going to workpiece changes with change in machine parameter. It has been observed from the literature that the researcher simply considered a variation of spark voltage in analysis as a significant parameter in deciding material removal rate. In this work is variation of fraction of energy is experimentally determined with process parameters by using heat transfer equations during the spark erosion process of EN-31. The results showed that the ratio of amount of energy going to workpiece and total energy generated at inter electrode gap ranges from 9.56% to 18.97%. So, fraction of energy which is going to workpiece at different machining process parameter changes significantly, which proves that the it has significant impact on material removal rate and should be considered in study of spark erosion process.