Abstract:In order to solve the problem of influence of selection of cutting parameters in CNC machining on machining accuracy, the model of milling force was established by taking the vertical milling tools as a research object. Through the establishment of vertical milling force model and force induced tool deflection models,the error expression in the z direction of tools were deduced,and the error model experimental system was established. Finally, by using orthogonal cutting test,reliability of the models is verified, and the influence of these cutting parameters to machining errors have been weighted in orderly way,which provides reference for selection of cutting parameters.