The invention relates to a music synthesis system for synthesizing a corresponding digital music output according to commands from a music data file. The music data file comprises a plurality of music data units. Each music data unit records related information of the music. The music synthesis system comprises a wavetable, a memory, a music analyzer, a wavetable preprocessor, and a synthesizer. The wavetable pre-stores the digital sampling data. The memory has a predetermined memory capacity for storing data. The music analyzer receives the music data file, analyzes the music data units of the music data file, and generates a corresponding analysis result. The wavetable preprocessor selects the digital sampling data with relatively greater importance in the wavetable and stores the selected digital sampling data in the memory. The synthesizer selects the digital sampling data from the memory and synthesizes the digital music output.