Abstract: The Intensity indicators of ground motion contain rich information about seismic motion characteristics and serve as crucial parameters linking seismic hazard to structural response. Selecting intensity indices of ground motion with high correlation to structural response can significantly improve the accuracy of evaluating structural seismic response. With the objective of seismic assessment for subway underground structures, this study conducted a systematic investigation into the selection of earthquake intensity indices for evaluating the response of underground structures in a Class II sites. Twenty near-field velocity pulse-type seismic motion records, twenty far-field harmonic-type seismic motion records, and twenty ordinary seismic motion records were collected. Numerical simulations were conducted on the seismic response of station-tunnel-site. Principal component analysis (PCA) was applied to analyze 12 intensity indicators, and the correlation between intensity indicators and structural response was explored. The results indicate that, in characterizing the seismic response of underground structures, near-field velocity pulse-type seismic motion exhibits the strongest correlation with velocity-type IM (i.e., PGV and SI), far-field harmonic-type seismic motion exhibits the strongest correlation with spectral correlation-type IM (i.e., SI), and ordinary seismic motion exhibits the strongest correlation with acceleration-type IM (i.e., PGA and AI); For the three types of seismic motions, there are proposed three composite intensity indices respectively as following: near-field velocity pulse-type seismic motion: ; far-field harmonic-type seismic motion: ; ordinary seismic motion: . Compared to single seismic motion intensity indices, the composite seismic motion intensity index IMp is more suitable for assessing the seismic performance of underground structures in the case.