The Circular Electron Positron Collider (CEPC) has been proposed for the Higgs and electroweak measurements with unprecedented precision. To achieve the required performance precision, it is necessary to understand, characterize and then mitigate the beam backgrounds from different sources that are critical for the machine and detector design and operation. In this paper, preliminary results will be presented for the beam backgrounds originating from the off energy beam particles. With the machine design presented in the CEPC Conceptual Design Report (CDR), detailed simulation including generation of the off energy beam particles originating from different processes and tracking of the particles has been performed. Four sets of collimators are introduced to prevent such off energy beam particles from re-entering the interaction region and reduce the background level.