Fourier transform infrared (FTIR) spectroscopy combined with hierarchical cluster analysis was used to study the influence of leaf senescence on magnoliaceae cluster. FTIR spectra of young, mature and old yellow leaves were obtained from 14 species trees belonging to the three magnoliaceae subtribes. Results showed that the infrared spectra of the three subtribes plant leaves were similar, only with minor differences in the absorption intensity of several peaks. Hierarchical cluster analysis was performed on the second derivative infrared spectra in the range 1 800～700 cm-1. The HCA results showed that the cluster based on mature leaves is better than that based on young and old yellow leaves. Our study suggests that it should be cautious to select leaf sample while using leaf spectra for classification.