针对我国现行《建筑抗震设计规范》中加速度反应谱长周期段尚存在的不足之处进行了探讨。按《中国地震动参数区划图》关于场地分类和地震动特征周期Tg的定义，从1146次震级大于5级的真实强震中筛选出7274条地震记录并进行分组。基于随机振动理论，由地震动Fourier幅值谱、功率谱和设计反应谱的转换关系得到统计意义上的能量密度分布和加速度反应谱，研究了地震动在长周期段的能量密度分布和加速度反应谱衰减规律。通过回归分析，对不同场地条件给出了设计反应谱长周期段合理的下降形式和斜率取值（周期延长至10s），为规范修订提供参考。

Deficiencies existing in China code of buildings aseismic design for long-period range of an acceleration response spectrum were analyzed. According to the definition of site classification and the seismic ground motion feature period Tg in the seismic ground motion parameters zonation map of China, 7274 ground motion records selected from 1146 real strong earthquake events with the rank  5.0 were divided into groups. Based on the random vibration theory, the statistical energy density distribution and acceleration response spectrum were obtained with the conversion relation among seismic ground motion’s Fourier amplitude spectrum, power spectrum and designed response spectrum. The attenuation laws of energy density distribution and acceleration response spectrum were studied. Through regression analysis, the reasonable descending form and slope value in long-period range of the designed response spectrum were deduced under different site conditions. The results provided a reference for the code modification.