An analysis of cutting force performance in the micro milling on steel has been carried out based on an experimental work using micro flat end mills on a precision CNC machine tool. It has been found that cutting forces occurred at low feed per tooth are relatively high by assessing the averaged peak forces from the experiments. When feed per tooth is relatively close to tool edge radius, the forces were not growing in linearity with the increasing feedrate. This finding indicates the significance of ploughing phenomenon as an effect of tool edge radius in micro milling.