在前人对三河—平谷地震研究的基础上，本文采用多震级、多破裂方式进行模拟，以开展三河—平谷地震的震级研究。首先，我们将研究区域的历史烈度曲线转化为峰值地面加速度（PGA）和峰值地面速度（PGV），随后将其与多震级、多破裂方式下的模拟结果进行对比。通过分析差异值，初步确定最贴近三河—平谷地震震级的三个可能值，分别为 M _W 7.8， M _W 7.9和 M _W 8.0。进一步比较这三个震级下的180种破裂模式及其产生的烈度空间分布形态与历史烈度形态的相似度，筛选出四种最相符的破裂模式。将这四种模式生成的烈度曲线与历史烈度进行对比，最终得出夏垫断裂在三河—平谷地区巨震的实际震级。研究结果显示，该震级小于人们通常认知的 M _W 8.0，更趋近于 M _W 7.9−或 M _W 7.8＋＋。 Abstract: Building upon previous studies of seismic activity in the Sanhe-Pinggu region, this study employs a multi-magnitude, multi-rupture approach to simulate the ground motion of the Sanhe-Pinggu earthquake, with a primary focus on investigating its magnitude. Firstly, historical intensity curves within the study area are transformed into peak ground acceleration （PGA） and peak ground velocity （PGV）. Subsequently, a comparison is drawn between these values and the simulated results under various magnitudes and rupture scenarios. Analyzing the differences, we preliminarily identify three potential magnitudes that closely align with the Sanhe-Pinggu earthquake: M _W 7.8, M _W 7.9, and M _W 8.0. Further, an in-depth comparison is conducted between the 180 rupture patterns associated with these three magnitudes, examining the spatial distribution of intensities and their similarity to historical intensity patterns. Four rupture patterns are selected as the most compatible. By comparing the intensity curves generated by these four patterns to historical data, the true magnitude of the Sanhe-Pinggu earthquake along the Xiadian fault within the region is ultimately determined. The research findings reveal that this magnitude is lower than the commonly acknowledged M _W 8.0, trending more towards M _W 7.9− or even M _W 7.8＋＋.