Recently, heart rate variability (HRV) as a non-invasive measure for assessing the balance of autonomic nervous system has drawn more attentions and HRV analysis has become a focus of the ECG signal processing. QT interval represents the ventricular repolarization duration. QTV might reflect the balance of autonomic nervous system in other way. QTV analysis might complement HRV analysis. Because of the difficulty in detecting QT interval, RT interval is often used instead of QT interval. HRV and QTV detecting methods have been presented in this paper. After recording 24 h ECG signals, R fiducial marks are detected correctly and ectopic beats are removed. T peaks are detected on the basis of templet matching and correlation. The analysis in frequency domain consists of 24 h 3-dimensional frequency chart, as well as trends of HF/LF and HF, with fast Fourier transform and autoregressive techniques. We acquired ECG signals from subjects under controlled respiration in different frequencies. The results of HRV and RTV spectral analysis have shown that HF peak is modulated at the frequency of controlled respiration, which proves that HF peak is dependent on the vagal activity and our method is correct. The establishment of these methods has provided a basis for further research, and the development of HRV and QTV analysis techniques will be more helpful for early diagnosis, monitoring and prognostic assessment of some diseases.