Many techniques have been applied for quality inspection but none is currently suitable for on-line bond quality inspection of uncured adhesive joined polymeric composites. A newly nondestructive evaluation (NDE) technique based on the interaction between ultrasonic oscillation and mediums (i.e., workpieces and adhesive) for inspecting the quality of uncured adhesive joined carbon fiber/nylon six composites has been developed. Ultrasonic oscillation was applied to adhesively joined carbon fiber/nylon six composites with various uncured bond discrepancies under a given static force. The interaction between ultrasonic oscillation and mediums led to the formation of internal friction heat, which softened the mediums and resulted in downward movement of horn. The horn displacements of workpieces with various bond discrepancies (i.e., lack of adhesive and air gap) were measured and compared with that of sound adhesively joined joint. Test results revealed that the horn displacement was closely correlated with volume of bond discrepancy (i.e., lack of adhesive and air gap), and therefore could be used to differentiate quantitatively the differences between a sound bond and a discrepant bond.