Abstract: Based on the electromechanical impedance and ultrasonic guided waves technologies,the location of damage in the composite beam was achieved by combining the data fusion arithmetic. Firstly,using respective characteristics of damage monitoring of the two methods,a kind of arithmetic called synthesized damage index was proposed to represent variations of tested structure. Location of damages in large region could be achieved with the two methods respectively. However the result was not accurate enough. Finally,the synthesized damage index was used to represent damages. The result shows that the location of damages can be recognized accurately with the synthesized damage index which is achieved by using data fusion. The damage location assessment is achieved.