The feasibility of ultrasonic scanning was studied in the micro-delamination detection of LTCC filter. Firstly, it was confirmed through theoretical calculations that the micro-delamination had an extremely high reflectivity to ultrasonic waves at the reference frequency, and the resolution requirements in the actual detection were explained. Secondly, ultrasonic test was applied to the filter, specific test suggestions were provided, and the defect information was identified according to test results. Then, the sample profile was prepared, and the defects were located according to the acquired defect information. Finally, the FIB etching technology was utilized to verify the inspection results and confirm the feasibility of ultrasonic detection of filter micro-delamination defects.