Numerous hard, brittle metals have been shown to form segmented chips during machining operations, which has been shown to be linked to high vibration levels in turning and milling processes. This article concerns quantitative comprehension of segmentation-driven vibration in end-milling process. First, dynamic model of milling process with impact of segmented chip is presented, and a periodic cutting force model related with segmented chip is proposed. Second, for experimental observation, a series of tests are carried out concerning modal test of cutting system; chip morphology, tool vibration during cutting, surface location error, and high-frequency sampling measurements of cutting force signal are realized. The method used for calculating the frequency of segmentation chip by oblique cutting is deduced. It is found that at low feed rate, the periodic cutting force is affected by the natural frequency of cutting system, segmentation chip, and tool vibration. Finally, amplitude–frequency response for quasi-single degree of freedom is employed to elaborate the relationship between segmentation frequency and natural modes of system. The results show that when the ratio (frequency of segmented chip to natural frequency of system) is a noninteger value or above 3, no significant vibrations of cutting system are observed in milling titanium alloy Ti6Al4V.