The present invention relates to medicine, namely to diagnosis of the cardiovascular system (CVS) on the basis of the ECG, and a method for evaluating the functional status of human CVS by recording the electrocardiogram (ECG) at least at one ECG lead, calculating the quantitative parameters of averaged cardiac cycle, heart rate variability (HRV), cardiac arrhythmia, disturbance in frequency and sequence of heart contractions, assessing the form of averaged ECG based on various mathematical methods, comprising the steps of: calculating normalized indicators by normalization of quantitative parameters on a scale from 0 to 100 conventional units - points, arranging these indicators and RQ into a hierarchical structure of 4 levels, where each level is formed by averaging the figures obtained at the previous level, forming the 1st level as a set of standardized indicators, forming the 2nd level as the 6 groups of related parameters with a close physiological content, including a group of amplitude-time parameters of ECG (1) responsible for operational control of the myocardium state, a group of HRV parameters (2) responsible for operational control of the regulation of cardiovascular, a group of cardiac arrhythmia parameters (3) responsible for operational control of the state of CVS, a group of amplitude-time parameters of ECG (4) responsible for the assessment of the myocardial reserves, a group of HRV parameters (5) responsible for the operational control of estimation of CVS reserves regulation, a group of cardiac arrhythmia parameters (6) responsible for the assessment of CVS reserves, calculating 6 generalized parameters by averaging the values of the individual parameters of each group, calculating 3 integrated RQ on the 3rd level, including RQ assessment of myocardial status as the average of parameters (1) and (4), RQ assessment of cardiovascular regulation as the average of parameters (2) and (5), and RQ diagnosis of cardiac rhythm disorders as the average o
