Abstract: Tensile samples with gas cavity defect, bar slag, incomplete welding defect were made to study the signal characteristic and relativity of parameter. The paper analyzed the characteristic and relativity of count, energy, amplitude of signal, and put forward the way to confirm one defect by parameter analysis, relativity analysis and cumulative analysis. Due to different figure and different mixture characteristic of one defect, the characteristic curve and characteristic point could be dissimilarity. It is then suggested to set up characteristic data of some defect and collect analysis to the data, which might effectively benefit the integraty of one equipment.