1. A system for recognizing physiological sound, comprising: a receiving module configured to receive a physiological sound; a feature extracting module configured to extract at least one feature from the physiological sound; and a classifier configured to classify the at least one feature to identify at least one category; wherein the feature extracting module comprises a voice activity detector (VAD) module configured to detect at least one segment from the physiological sound, a Mel-frequency cepstrum coefficients (MFCC) module configured to transfer the at least one segment to at least one MFCC feature vector, and a K-means algorithm module configured to find at least one representative data point from the at least one MFCC feature vector, wherein the at least one segment from the physiological sound comprises a first heart sound or a second heart sound, the feature extracting module is capable of calculating heart rates of the first heart sound or the second heart sound and calculating a modulus of differences between two adjacent heart rates, the classifier is configured to classify the at least one feature based on the modulus of differences between two adjacent heart rates to identify at least one category.