Ultrasonic wave testing is a classic Non-destructive testing (NDT) method to detect, locate and monitor the crack/fracture in construction materials. However, it is still hard to examine those small abnormal bodies since effective reflected signal from abnormity is usually rather weak. In this paper, a new ultrasound imaging technique, equivalent offset migration (EOM), is studied to demonstrate the feasibility and applicability for detecting concrete cracks. Thus, a complex numerical model along with six small scale flaws was built, and then the ultrasonic wave propagation in concrete was modeled by high order finite difference approximation method. Numerical simulation indicates that 1) there exists a strong scattering phenomenon while ultrasound propagates in concrete with multiple small scatter flaws, and 2) EOM is capable of imaging small flaws in concrete with high resolution and accuracy.