Surface integrity is becoming important to satisfy the increasing requirements service life of machined parts. The purpose of this study is to investigate the effects of cutting speeds on surface integrity of Inconel 718. Experiments are conducted on a CNC machining center under various cutting speeds. The machined surface integrity is evaluated in terms of surface roughness, microhardness and residual stress. Experimental results show that machined surface integrity of Inconel 718 is sensitivity to the variations of cutting speeds. The surface roughness firstly increases with the cutting speeds increasing at the range from 50 m/min to 200 m/min, then decreases with the further increasing of the cutting speeds. For microhardness, it can be seen that work-hardening for the machined surface is serious. The surface residual stresses are tensile ones at the range of the selected cutting speeds from 50 m/min to 3,000 m/min in this research.