Abstract
In order to conduct Non - Destructive stress wave velocity measurement for Young's modulus on existing wooden buildings, we improved the conventional test by comparative studying other material test methods, designing an assistant device for the test, proposing corresponding operating method and calculating method for Young's modulus. Besides, the effectiveness common used corrective value has been doubted, and result of improved the test has been verified. Young's modulus could be obtained by changing distance between sensors without using corrective data.