Titanium alloy tubes were an ideal material to replace steel tubes. However, the relationship between piercing temperature and dimensional accuracy for titanium alloy seamless tubes was unclear. Therefore, the effects of piercing temperature on the stress—strain distribution and dimensional accuracy of Ti80 titanium alloy were studied using thermal simulation compression tests, finite element numerical analysis optimization and optical microscopy. Pierced at 1050 °C, Ti80 titanium alloy was cross-rolled and perforated to obtain a capillary tube, whose dimensional accuracy was better than that of those pierced at 850 °C and 950 °C. The microstructure of Ti80 seamless tubes was layered α-Ti, grain boundary β-Ti and a Widmannstatten structure. The tensile strength, yield strength and absorbed energy were 867 MPa, 692 MPa and 52 J, respectively.