Knee joint surgery for artificial joint replacement is common in orthopedic surgeries. In this operation, there is a need to prepare the surface of the cortical bone for mounting the artificial joint. Therefore, milling process is frequently performed. Since the surgeon should be careful not to hurt bone tissue and neurons and also minimize waste of blood, the operation should be performed in the shortest possible time. This study, for the first time, focuses on modeling and optimization of effective parameters of bone milling including cutting speed, feed rate and tool diameter on surface roughness and material removal rate using response surface method. Results showed that in order to achieve maximum surface quality, minimum feed rate, maximum tool diameter and down milling procedure should be selected. On the other hand, the maximum material removal rate coincides with maximum feed rate and tool diameter. Therefore, cutting speed of 3000 rpm, feed rate of 50 mm/min, tool diameter of 5mm and down milling procedure can satisfy both high surface quality and high material removal rate.