Abstract: By taking into account the scale effects,a micro-ball-end cutting force model is established.Firstly,the cutter is simplified as a ladder shaped cantilever beam.Secondly,virtual displacement principle is combined with machine-workpiece system deformation to obtain the cutter deformation with micro-ball-end cutting force.Thirdly,the deformation is coupled into the cutting edges trajectories.Finally,a new milled surface topography model is developed,which synthetically considers spindle runout,minimum chip thickness,cutter deflection and machine-workpiece system deformation.An algorithm for physical simulation of three-dimensional micro-ball-end milled surface topography is proposed.A simulation example is given and the factors affecting the milled surface accuracy are analyzed.Experimental results demonstrate the validity and the applicability of the algorithm.