The invention discloses a network source oscillation modal identification method based on phasor grouping rendering. The method includes the following steps of: obtaining a certain same frequency oscillation power of each power supply node through spectrum analysis, and the corresponding amplitude and phase; using a pointer phasor, at each power supply node, to represent the size and direction of the oscillation power of each power supply node; dividing each power supply node into two groups according to the condition that whether an included angle of each phasor and a reference phasor is more than 90 degrees; and rendering the power supply nodes with different colors. Thus operation staff can obtain the information that between which power supply nodes the oscillation power is exchanged, where an oscillation center is, and which power supply nodes have maximum contribution to the oscillation. The defect that traditional oscillation analysis results cannot give the oscillation modal results is overcome.