Micro milling is widely used for producing industrial micro parts. In micromachining, approaching the depth of cut to tool cutting tip radius causes some problems in achieving desired surface quality and burr formation. It is impossible to use conventional deburring methods in micro parts due to the reduction of machining scale and the importance of high dimensional accuracy and surface quality. Therefore, it is important to comprehend micro end milling and the effect of process parameters on reducing these problems. In this study, the effect of spindle speed, feed rate and depth of cut on surface roughness and burr size during micro end milling of AISI1045 steel have been investigated using the response surface method. Two flute endmills with 0.8 mm diameters have been used in this study. Results show that feed rate with 55.26, 37.53 and 44.55 percent contribution on burr size in up milling side, down milling side and surface roughness is the most effective parameter in the micro end milling process. Selecting the maximum amount of spindle speed, feed rate, and the minimum amount of depth of cut causes minimum burr size in both up milling and down milling side. 36000RPM spindle speed, 5.7mm/s feed rate and 0.086 mm depth of cut causes the best surface quality in micro-milling of mentioned steel.