Negative emotions may affect the quality of life and the function of the cardiovascular system. The purpose of this study is to detect negative emotion symptoms using the heart rate recovery and decay time constant. Twenty seven subjects were recruited for this study with informed consent and Institutional review board approval. The subjects were divided into the negative emotion group and normal group based on tests of Hamilton's Depression and Anxiety Scales. During the experiment, the electrocardiograms (ECGs) for all subjects were continuously recorded, and the related RR intervals were measured for later analysis. Nine subjects having the HAM-D ≥ 10 or HAM-A ≥ 18 are defined and collected to be the negative emotion group. From the experimental results, the heart rate recovery of 1 min (HRR1min), 2 min (HRR 2min), and 3min (HRR3min), chronotropic response, and the time of twelve-beats heart rate decay (T12beat) after maximal exercise test are statistically significantly different between the groups of normal and negative emotion symptoms. It is demonstrated that the heart rate recovery and time of twelve-beats heart rate decay are the useful and objective index for negative emotions detection.