Reflection seismology has been widely used in the petroleum exploration industry for decades. To improve the capabilities of detecting the depths and lengths of cracks inside a concrete element, an ultrasonic common depth point (CDP) reflection technique was employed in this study. The effectiveness and accuracy of applying the reflection seismology method to detect cracks embedded in concrete structures are discussed. Test results show that simulated blind cracks with certain lengths, dip angles and depths inside concrete specimen can be successfully imaged and identified. This study shows that when the signals reflected from the crack are obscure, the CDP signal stacking method is very useful and provides an opportunity to look into the object, which is not possible with traditional ultrasonic methods.