The aim of this study is to evaluate the change of the quality of processed goods of fabrics on processing line by nondestructive acoustic measurement. The relation between the measurement of acoustic transmission and the measurement of static tensile test is required. The following three facts about the sound velocity are acquired by experiment: 1) It depends not only on tension, but on structure of fabrics; 2) It gets faster according to the increase of tension; 3) There is a little difference in it under the tensile states of uniaxial extension and biaxial extension.