The difference between the diffraction peak position of α phase (0002) and β phase (110) of TC16 (Ti-3Al-5Mo-4.5V) titanium alloy is less than 0.1°. Due to the increase of β phase content, the two peaks overlap severely in the traditional X-ray diffraction test optical path. At present, the α+β two-phase TC16 titanium alloy texture cannot be measured. In this paper, overlapping diffraction peaks were separated from the hot rolled annealed TC16 titanium alloy bar diffraction pattern. The microstructure, texture and mechanical properties of TC16 alloy bar were studied by optical microscope, X-ray diffraction and Vickers hardness tester. The shape of the diffraction peak was fitted by the Cauchy square function on the Matlab platform, and the influence of the change of diffraction optical path parameters on the broadening and overlapping of the α phase diffraction peak and the β phase diffraction peak was investigated. The results show that the X-ray diffraction optical path configuration of the polycapillary and parallel long sola slit solves the problem of overlapping diffraction peaks and improves the accuracy of texture measurement; The test found that there are mainly two texture components in hot rolled annealed TC16 bar, which are <0002> and <101(-)0> double wire texture; The texture makes the transverse tensile strength of TC16 less than the longitudinal tensile strength, the effects of texture on the mechanical properties of titanium alloy are discussed. This research has important theoretical and engineering significance for improving the performance and processing technology of titanium alloy fasteners. At the same time, it also provides a solution for the accurate measurement of the texture of two-phase titanium alloys.