Abstract: The Ni-Ti alloy hung of a bone conduction bluetooth earphone appearred to be soft after assembly,and early fracture occurred during fatigue test.By means of macroscopic observation,chemical composition analysis,tensile test,metallographic inspection,fracture analysis,energy spectrum analysis and so on,the reasons for fracture of earphone were analyzed.The results showed that the raw material of Ni-Ti alloy hung of the earphone form folding defects during the rolling process.During the subsequent drawing process,the folding defects continued to extend to the inside of the material,forming longitudinal cracks,and the ability of the material to withstand external forces was reduced.As a result,the earphone hung appearred to be soft when it was in use,and early fracture occurred during the fatigue test.