Electrical Discharge Machining (EDM) is a non-conventional cutting operation for based of materials removal to the core fact which conceder insignificant force of tool is created through the process of machining. Also, EDM used in produce hard materials that have electrical conductivity. In EDM process, the pivotal topical parameters are Material Removal Rate (MRR), Surface Roughness (Ra) and Micro Hardness (HV). The traditional try and error way to define the influence the parameters of machining on the objective parameters is time consuming as well as high cost. The aim of this work is to evolve a mathematical model using multiple regression to describe the effecting of three machining parameters (pulse on time, pulse off time and current) on the objective parameters. 27 samples were run by using computer numerical control based EDM machine which used for machining steel 304 with a dielectric solution of gas oil by using DC current values. Three predicted models have been developed using multiple regression methods show a reliable accuracy to be used in this kind of cutting process. The result of this work is helpful to be performed in the industry to decrease the time and cost in MRR, Ra & HV prediction