Theoretical and experimental research on removing characteristics of ultraprecise bonnet polishing methods are made to get an ultra-smooth surface for optical elements. A material removing model of bonnet polishing processional motion is established according to kinematic principle based on Preston equation. The model is modified in terms of Hertz contact theory using the physical characteristics of polishing bonnet tools. The affect of several main technological parameters to removing characteristics of processional polishing motion is analyzed by means of computer simulation, and an orthogonal test is made on an ultraprecise numerical control polishing machine. The simulation results fit well with test results and four important conclusions on bonnet polishing technology are obtained. The span of processional angle and decrement is provided and an ultraprecise smooth surface with RMS=0.024 λ figure precision is achieved, which provides theoretical foundation to research on bonnet polishing technology of optical elements.