The invention discloses a singing grading system and a method thereof. The method comprises the following steps: performing note segmentation and note quantization on singing voice signals, searching the corresponding singing song fragments in songs, computing a plurality of distances and comprehensively obtaining a singing score. The system and the method can help a singer obtain relatively exact score as long as singing data have better consistency with original voice in terms of rhythm, meanwhile, the grading system performs matching by a positioning technology without complete synchronization between the singing and accompaniment, which causes the system to evaluate the singing fragments of the singer without depending on inputting synchronizing information or requiring the singer to sing a song from the beginning to the end.