Titanium alloy has heat resistance, corrosion resistance, and light weight properties. Because of its high specific strength, it is used in various mechanical structural parts to reduce the weight of aircraft and automobiles, and is also used as engine parts because of its heat-resistant properties. Also, due to its high biocompatibility, it is widely used in medical products such as implants and artificial bones.Titanium alloy has low thermal conductivity, so the cutting temperature rises high, and chattering is easy to occur due to its low modulus of elasticity. Therefore, the tool life is shortened and the surface integrity and machining precision are deteriorated.In general, aircraft parts of titanium alloy are designed with various types of thin-walled structures in order to maximize the effect of weight reduction. When milling a thin-walled structure, it is difficult to maintain dimensional accuracy due to machining deformation and vibration. In particular, when machining corners in a thin-walled structure, shock and vibration are likely to occur because the cutting area increases rapidly. They create tool marks on the machined surface, which deteriorate the surface quality, and shorten the tool life by breaking the cutting edge. In this study, the machining characteristics of titanium alloys widely used as aerospace parts were investigated. In order to improve productivity and machining quality, the effective range of cutting parameters and optimal values were derived. In order to find an effective machining method for milling of thin-walled structures common to aircraft parts of titanium alloys, machining experiments were conducted on the basic shapes of ‘ㅡ’ and ‘L’-shaped thin walls. To optimize the E-shaped thin-wall milling, cutting simulation was performed to derive effective cutting conditions and tool paths. To verify this, a cutting experiment was performed. And it was confirmed that the optimization was successfully conducted through comprehensive analysis of the machining surface, dimensional error, tool condition, and cutting signal.The results of this study on the milling process of thin-walled titanium alloys are expected to contribute to the improvement of machining quality and productivity by applying them to actual aircraft parts machining.