Abstract: It is of great significance to obtain the aerodynamics of stay cables to improve the safety and economy of bridges. However, under various effects, the cross-sections of stay cables during service might tend to be non-standard circle. It is necessary to investigate the wind-induced vibration characteristics of the non-standard circular stay cables. Three elliptical cylinders were used, with major-minor ratios of 1.05, 1.10 and 1.15, to investigate the time-frequency characteristics of vibration of non-standard circular stay cables. The results show that the time histories of the observed vibrations could be classified into two categories. One is a very stable periodic motion, which is similar to the simple harmonic motion. While the other is not particularly stable, with small amplitude in one period and large amplitude in another period. In most test cases, wind-induced vibration lies in the first category of vibration, more stable and with larger amplitude. The vibration frequency of the model is generally around the natural frequency. When the vibration is violent, the vibration frequency begins to deviate from the natural frequency. The cause might be the additional negative aerodynamic stiffness or mass induced by the large-amplitude vibration.