This is one analysis method about probing into relationship of beating signal and heart function. It is used to deal with one beating signal, which is measured from one subject under any activity condition in a period of time with an electric manometer. And this analysis could be the reference target of the heart function of the subject. This method includes: (1) to transform the beating signal into the power spectrum, (2) to normalize the outcome of the power spectrum transformation, and (3) to compute an advance defining heart index from the normalized power spectrum diagram, and supply the reference target of the heart function from the subject with the heart index.