This research interesting to study effect of machine conditions end mill on the surface roughness for 1020 carbon steel. In this Paper, propose multiple regression model (MRM) by using response surface method (RSM) in Minitab program, to predict surface roughness and study the effect of the spindle speed, feed rate and depth of cut on the surface roughness. The R2 (ability the Independent values to predict the dependent values) of the predictive model is 95.51%. From the applicant multiple regression model equation, the depth of cut (X3) is the most significant machining parameter to influence on surface roughness (Ra).