Beam structures are a common form in many large structures, and therefore the real-time condition monitoring and active control of beams will improve the reliability and safety of many structures. This paper presents a damage assessment method which combines the impedance method and guided wave method. The combination enabled to improve the damage detection efficiency. The impedance method is used first to detect whether the damage occurs or not and judge the damage extent. The guided wave then is introduced to accurately localize damages. The improved method provides possibility for more accurately identifying and localization damages compared to that conventional method. A powerful wavelet transform is used to extract the signals efficiently. Additionally, with using the general function generator to excite the piezoceramic (PZT) patches to generate the guided wave, the guided wave propagates along with the beam structures with PZT patches bonded, and the real-time signals are recorded. Damages are indicated by a change of response signals when compared with a template undamaged condition. The wave attenuation and mode conversion is sufficient to detect various types of defects. The results show considerable ability for identifying and localization of the simulated damages.