The site amplification effect is a key issue in ground motion simulation and engineering seismic design, in which crustal amplification effects caused by variations in velocity structures at the crustal scale significantly influences the amplitude and frequency content of seismic waves. The complex geological structure and the lack of sufficient[ ] strong-motion observation data in eastern China pose challenges to empirical evaluations of crustal amplification effects. Based on shear-wave velocity structure models of three tectonic subregions—the Sino-Korean Platform (SKP), the Yangtze Platform (YZP), and the South China Fold System (SCF)—this study systematically calculates and comparatively analyzes the frequency-dependent crustal amplification factors for each subregion using the Square-Root Impedance (SRI) method combined with Boore"s empirical density formula. The results indicate that the crustal amplification factors in the three subregions exhibit a significant frequency dependence, with amplification primarily concentrated in the 1–10 Hz frequency band. The peak amplification factors for SKP, YZP, and SCF are 2.96, 2.70, and 2.65, respectively. Notable regional differences are observed, with the SKP region displaying the strongest amplification, mainly controlled by the combined effect of its low near-surface shear-wave velocity (1.20 km/s) and quality factor Q. The amplification factors for the YZP and SCF regions intersect near 2 Hz, reflecting the differing contributions of mid-deep and shallow velocity structures to the amplification effect across frequency bands. A comparison with North America further reveals that the amplification characteristics of the three subregions in eastern China lie between those of western and eastern North America, bearing a distinct imprint of geological evolution. The findings of this study provide a theoretical basis for ground motion simulations, seismic hazard zoning, and engineering seismic design in eastern China. Furthermore, the SRI method offers an effective approach for evaluating crustal amplification effects in regions lacking strong-motion data.