Seven thousand seven hundred and seventy eight ground motion records were collected. For each group of seismic ground motion, the spectral characteristics were analyzed. A type of ground motion clustering method based on energy distribution was introduced. According to this method, the records belonging to the same site type can be divided into three parts. For each group of seismic ground motion, the characteristic periods were proposed based on the Chinese seismic resistance code. Besides, the differences between the proposed value and the code value were analyzed. The research shows that, compared with the proposed values, the code characteristic periods of group 1 and group 2 are bigger, while the values of group 3 are smaller.