This paper proposes a method for the multi-pitch estimation of polyphonic music signals. Instead of on the frame level, the estimation is based on the Partial Event, which is defined like the note event in MIDI. All partial events in a piece of music are extracted dynamically in the process of the frame by frame Short Time Fourier Transform (STFT). For each event, Net Support degree received from other events is calculated and the events with the highest support degrees are selected to be the fundamental frequency (F0) events. From another point of view, the support is transferred from higher frequency partial events to lower ones and finally concentrated on the F0 events. This method can estimate the number of concurrent sounds, the onset and offset times of the notes. Experiments on both randomly mixed chord signals and synthesized ensemble music signals in “wav” format are conducted and the results are promising.