The invention discloses a voltage stability discriminating method of a DC receiving-end AC system based on dynamic tracking of abnormal fluctuation of a WAMS. The method comprises that 1) voltage fluctuation waveforms of recent abnormal fluctuation information are extracted and counted, and an operation manner in which voltage jittering occurs frequently is determined; 2) a sample of fluctuation data is collected, and attributes of the sample are characteristic attributes in different operation manners; 3) collected information is clustered, the second attribute represents a damping ratio of a dominant frequency, and the sixth attribute represents a coefficient of the abnormal voltage fluctuation level; 4) a sample point of an information pair of highest fitness serves as a first clustering center; 5) the sample point of the information pair is corrected; and 6) all clustering center points and clustering amount H are determined, analysis is made by combining trend condition and power-on condition, a voltage stability level criterion is formed, and thus, the voltage stability of the DC receiving-end AC system is determined. The method is low in computational complexity, easy to realize online, and can realize rapid determination for voltage instability problems of the DC receiving end and reasonable construction of a linked fault set.