High speed milling of titanium alloy is widely used in aviation,aerospace,ship buliding and military manufacturing industries for its high efficiency,good quality and little machining deformation.〖KG-*3〗Aiming at high speed milling technology of difficult-to-cut material TC4 (Ti-6Al-4V),with the orthogonal experiments considered of four factors and three levels,the influence of milling depth,milling width,feed per tooth and spindle speed were analyzed. The cutting force obtained during milling process were divided into tangential cutting force,radial cutting force and axial cutting force,multiple linear regression was used to establish the three directional cutting force model. To evaluate the performance of the cutting force models,a new cutting experiment was designed. The results show that the cutting force models are accurate and can be used to predict three directional cutting force.