Abstract: In ultra-precision flycutting, the 3D topography of the processed surface mainly includes roughness, waviness and surface shape. These characteristics are affected by different surface quality factors. In order to study the influence of different factors on the surface quality, the influence factors of ultra-precision flycutting were analyzed. Then, based on the principle of blade copying, a simulation model of 3D shape of ultra-precision flying cutting surface was established. Finally, the influence law of main factors such as process parameters and relative vibration of cutler-work was analyzed using this model, and the relationship between the main spatial frequencies of the processed surface and the relative vibration frequencies was obtained.