This paper describes a primary study for a new method of enhancing measurement with using an impedance analysis method that is applied to structural health monitoring. The goal of this research is to show basic information that is used to evaluate the structural health condition with using piezoelectric sensors. We present a study for the development of a practical and quantitative technique for the assessment of the structural health condition with using a piezoelectric impedance-based technique that is associated with longitudinal wave propagation. The natural frequency has a tendency of frequency shifting with respect to the hole size that corresponds to the real structure’s crack size. To numerically estimate the damage condition, we suggest the Cov (Covariance) and CC (Correlation Coefficient) evaluation methods.