Attenuation of defect reflection signals, superposition of multiple defect reflection signals, and defect shapes are key factors that affect the recognition of defect features during the analysis of low-strain curves. In view of the difference in the attenuation coefficient of wave propagation before incidence and after reflection at the defect interface and the superimposed interference of defect reflection, this paper obtains the attenuation coefficient of wave propagation by partially fitting the measured reflection wave curve with the theoretical reflection wave curve of an intact pile segment and utilizing superposition correction. In addition, the paper proposes an improved method for calculating the integrity coefficient based on measured curve fitting. At the same time, based on the transient response simulation technique of gradually varied defect piles in stratified soil, this paper puts forward the method of further analyzing defect features with integrity coefficient. Finally, the paper verifies the effectiveness of the method by employing the measured reflection wave curve.