Abstract: The unequally thick segment was regarded as research objects. The focused probe was employed for testing the unequally thick segment. The ultrasonic testing and signal processing of adhesive structure of the unequally thick segment were mainly studied. According to the feature of the bonding and debonding signal, the method of equal thick magnitude combined with bandpass filter was used for processing echo signal, the clear debonding figure was obtained at last. The ultrasonic testing system and signal processing method based on the above technique could fleetly and accurately test the unequally thick segment.