The performance and defect detection of Low-Emissivity (Low-E) glass are of great significance in its production. Currently, for Low-E glass with single, double, or multiple silver coatings, defect detection mainly relies on the analysis of visible light images, which presents certain limitations such as insufficient contrast and low identification efficiency. Terahertz waves can penetrate most non-conductive materials, making them highly effective for internal defect detection and structural analysis. Therefore, in this study, Terahertz Time-Domain Spectroscopy (THz-TDS) and scanning imaging technology based on this principle are employed to detect the coating structure and surface scratches of Low-E glass. By utilizing reflective THz-TDS and scanning imaging techniques, the waveform and intensity of the reflected terahertz pulse signals from glasses with different coating structures are investigated and the defect imaging is successfully achieved. This study demonstrates the feasibility of THz time-domain spectroscopy in the identification of glass coatings and defect detection.