This issue is to figure out the feature of AE signals ,which are produced by the cracks in Titanium Alloy of TC18,when the crack gives its birth,and grows until when the TC18 sample is broken. TC18 samples and fatigue test are designed , and AE signals are acquired along the test . Make clear the feature parameters of time domain and frequency domain using parametric method . Give the reference comments of AE monitoring in Titanium Alloy of TC18 samples.