Abstract: Compared with conventional deformed aluminum alloy, SiC_p/Al composites have three typical defects, such as Al segregation, poor SiC_p band (Al wire) and SiC_p agglomeration. The typical defects had low detection ability and large quantitative deviation, when the conventional A-type pulse reflection method was used to detect. In order to solve the problem, the same simulation test block as the typical defect interface was designed to adjust the detection sensitivity, and the phased array detection method was used to detect the materials. The results show that, the difference of acoustic impedance between defect and material being inspected, and the relationship between ultrasonic beam and defect location are the main factors that affect the defects detection ability and quantitative deviation. The new method combines the calibration sensitivity of simulated test block with the scan test method of multi angle control array, which can effectively solve the problems which are difficult to find the defects of Al segregation, Al wire and SiC_p agglomerated. And meanwhile, it can improve the accuracy of defects quantification.