This paper studies the formation mechanism of surface waviness in ultra-precision grinding. A dynamics model of the aerostatic bearing wheel spindle is developed to discuss its vibration characteristics. The surface waviness formation models are established considering the wheel spindle vibration (WSV) and non-uniform wheel topography (NWT) as the origins of waviness. Grinding experiments are conducted. The results show that the WSV has less influence on surface generation at higher frequencies and speed ratios. In addition, the NWT plays a major role in the waviness formation for the coarse wheel, whereas for the fine wheel, surface waviness is primarily influenced by the WSV, especially at the fundamental frequencies. This study is useful for optimizing grinding conditions to improve surface quality and tribological properties.