To address the issue of significant attenuation and strong scattering of ultrasonic waves in solid propellants， which prevents existing ultrasonic transducers from detecting all internal defects， a nondestructive testing research method using ultrasonic laminated transducers is proposed. Based on the research of domestic and international scholars， this study first proposes leveraging the high transmission energy characteristic of laminated transducers to mitigate attenuation and scattering problems during ultrasonic propagation in solid rocket propellants. A 1 MHz four-layer ultrasonic transducer is designed. This transducer converts a planar acoustic field into a cylindrical acoustic field through crystal stacking， thereby enriching echo information and improving defect resolution. Based on acoustic field simulations of the ultrasonic laminated transducer， a 1 MHz four-layer ultrasonic transducer is developed. Experimental comparisons with domestic and international transducers of similar specifications show a 20 dB improvement in gain. Finally， an ultrasonic automated inspection system for solid rocket propellants is established， enabling online inspection of solid rocket propellants. The results indicate that the developed inspection equipment can accurately detect the smallest artificial blind holes measuring Φ1.2 mm × 5 mm （depth） as well as natural inclusion defects， achieving qualitative and quantitative nondestructive testing of all internal defects in solid rocket propellants.