This paper analyzes and discusses the winding vibration characteristics of a permanent magnet synchronous generator (PMSG) before and after demagnetization fault. Firstly, the winding electromagnetic force (EF) under both normal and fault conditions is deduced, and a simple forced vibration model of the end winding is established. Then, the end winding EF and vibration characteristics are analyzed. Finally, specific working conditions are calculated and verified through finite element analysis (FEA), showing consistency with theoretical conclusions. The results show that under normal conditions, the end winding exhibits vibrations at even multiples (mainly twice) of the electrical frequency. After the demagnetization fault, the double frequency vibration of the winding persists, and the fractional frequency components of n/p electric frequency emerges. In addition, the amplitude of the double frequency decreases as the degree of demagnetization increases, while the amplitude of the fractional frequency components increases with the degree of demagnetization. When the total degree of demagnetization is the same, different demagnetization ranges and positions have no effect on the double frequency amplitude. However, a larger demagnetization range results in a smaller amplitude of the fractional frequency components. But different demagnetization positions have no significant effect on the frequency components and amplitude of winding vibration. After a uniform demagnetization fault occurs, the frequency components of the winding vibration remain largely unchanged compared to normal conditions, but the amplitude of the double frequency decreases. These results can provide a reference for the health management of permanent magnet synchronous generators, helping to ensure the safe and stable operation of wind turbines.