In this paper, we defined and investigated multifractal singularity spectrum area lnsf(α) of the 12-lead ECG signals taken from healthy and diseased human subjects of different age stages. One-way ANOV A analysis reveals all the crowds are statistically distinguishable using this indicator. The results showed that the arithmetic mean values of lnsf(a) from the 12 leads ECG signals is significantly larger for healthy young people but smaller for heart diseased sufferer. While the dispersion of lnsf(a) from the 12 leads ECG signals is obviously smaller for diseased sufferer but larger for healthy people. We also think, the 12-leads mean value of singularity spectrum area of human ECG signal can reflect the self-discipline control function of human autonomic nervous system to some degree. When people are getting unhealthy and older, the self-discipline function weakens. It tends to turn from multifractality to monofractality.