To screen out the basin long-period ground motion inputs, which could be used for the seismic design of supper high-rise buildings in basin, the formation mechanism of long-period ground motions was explained. Then, the dominance of surface wave in long-period ground motion was analyzed, and an approach to extract the coda waves of ground motions, which were dominated by surface waves, was put forward. Finally, the discriminant criterion of long-period ground motion was proposed through statistical analysis based on the characteristics of coda waves. The results demonstrate that the propagation, overlapping, and frequency-dependent amplification of the surface waves are generated by conversion of body waves at the boundaries of deep sedimentary basins, and plains are the main formation mechanism of long-period ground motions. The surface wave components in the coda waves of long-period ground motions are responsible for the maximum responses of long-period structures, such as supper high-rise buildings. The discriminant criterion of long-period ground motion is concluded that: the predominant period of velocity response spectrum (Tp) of ground motion is larger than 2 s, in addition, the ratio of the amplitude in the predominant period of velocity response spectrum associated with the extracted coda waves and original wave is greater than 85%.