This paper firstly introduces the basic knowledge of music. proposes the detailed design of a music retrieval system based on the knowledge of music. and analyzes the feature extraction algorithm and matching algorithm by using the features of music. Feature extraction of audio data is the important research of this paper. https://www.roneverhart.com/MagnaFlow-2000-Dodge-Dakota-California-Grade-CARB-Compliant-Direct-Fit-Catalytic-Converter/