In order to detect plant aroma in a natural environment, we have investigated roses' aroma using an odor sensor of quartz crystal resonator (QCR).In present work, we describe experimental setup for real-time sensing of roses' aroma and feature extraction of roses' aroma sensed by QCR sensors. This method can distinguish as different aroma as human sense of smell judged for two kinds of roses. We measured one rose's aroma 3 times repeatedly in first day, second day and third day, respectively, and the result shows that rose aroma of first day is different from the ones of the other two days.