Abstract: Titanium alloy was largely used in the joint of central wing and outer panels of some new type military aircraft. Acoustic emission (AE) monitoring of the material might face great difficulty in the process of fatigue test of some pivotal parts because of its acoustic anisotropy and high acoustic attenuation coefficient of titanium alloys. So the understanding of characteristics of AE of titanium alloys and providing effective AE signal identification means was obviously very important. This paper introduced the method of analyzing AE signal of titanium alloys by applying wavelet packet and AR spectrum. With the help of these discussions, it was seen that wavelet packet was able to extract specific frequency segment effectively, when detecting crack expending of titanium alloys and their components was very difficult by means of traditional parameter analysis. The combination of wavelet packet with AR spectrum provided credible basis for identifying the crack expending of titanium alloys parts and it showed that signal processing had great potential in AE monitoring of structure integration.