A system, a method and a recording medium for calculating a physiological index are provided. The method includes: dividing a physiological data sequence into a plurality of windows analyzing a data segment in each window to obtain metadata that represents data characteristics of the data segment updating the metadata including the data characteristics of all data segments in the windows up to a previous window by using the metadata corresponding to one of the windows to obtain the metadata including the data characteristics of all data segments in the windows up to a current window and finally, calculating the physiological index by using the updated metadata.
