In this paper, a singing voice splitting (SVS) system is researched and implemented by short-time Fourier transform (STFT) and Nonuniform Discrete Fourier Transform (NDFT). Specifically, there are four processes: T-F decomposition, main pitch detection, T-F information extraction and singing synthesis. Firstly, choose STFT as T-F analysis tool. Then, use NDFT realizing main pitch detection. Next, extract various order harmonics of each frame of music signals, getting the short-time spectrum. Finally, gain singing signals from the short-time spectrum by overlap-add (OLA) algorithm. The experiment result shows that the SVS system based on STFT and NDFT can effectively split singing signals.