统计分析了１９５４年以来中国大陆发生的２０≤ＭＳ≤５５近２００次中小地震的烈度关系律，并与ＭＳ≥５０的中强地震统计规律进行了比较。结果表明，中小地震和中强地震的烈度分布都有相似的区域特征，如东部烈度的衰减慢于西部，等震线长短轴比小于西部等。结果还表明，对于一个固定震级，由中小地震统计的烈度衰减律在烈度高于Ⅴ＋时快于中强地震的统计值，而当烈度低于Ⅴ＋时又慢于中强地震的统计结果；此外，在烈度－震级等关系方面，中小地震和中强地震的统计规律也有一定差异。这些差异说明，在使用当前较普遍的中强地震统计关系时，对于５级左右下限地震烈度分布要考虑其不确定性，今后应建立包括小、中、大各种震级的统一烈度分布规律 The law of intensity of 20≤MS≤55 nearly 200 medium and small earthquakes occurred in mainland China since 1954 has been statistically analyzed and compared with the statistical laws of moderate-strong earthquakes of MS≥50. The results show that the intensity distributions of medium and small earthquakes and moderate earthquakes all have similar regional characteristics. For example, the decay of the eastern intensity is slower than that of the western part, and the ratio of the long-short axis of the isoseismic line is smaller than that of the western part. The results also show that, for a fixed magnitude, the intensity decay law calculated by medium and small earthquakes is faster than that of moderately strong earthquakes when the intensity is higher than Ⅴ +, and slower than that of moderately strong earthquakes when the intensity is lower than Ⅴ + There are also some differences in the statistical laws of medium and small earthquakes and moderate earthquakes in the relationship between intensity and magnitude. These differences indicate that the uncertainty of seismic intensity distribution should be considered for the lower limit of about 5 when using the currently most common strong seismic statistical relationships and a unified intensity distribution including various small, medium and large earthquakes should be established in the future