Based on the Lamb wave damage detection for the plate structures by using the piezoelectric transducers, a non-reference damage detection method using the single mode Lamb wave is proposed and a damage detection experiment on an aluminum plate is carried out. According to the theoretical model of piezoelectric transducer, the damage reflection echo signals from the detection signal of the damaged plate is accurately identified by selecting the detection frequencies of single mode Lamb wave in the experiment. The distance between the damage and the transducer is calculated through the propagation time of the damage reflection wave and the corresponding group velocity. Aiming at the error in distance calculation caused by the difference between the theoretical group velocity and the experimental group velocity, an improved calculation method is proposed, which reduces the error to less than 3%. The results show that the damage scattering signals in the structure can be identified using the single mode Lamb wave, and the distance between the damage and the transducer can be calculated effectively.