The present invention discloses an omnidirectional image processing method and device. Format information is extracted from a code stream, positions in a decoded omnidirectional image is mapped to positions on a sphere by using a special mapping relationship according to the format information, and the decoded omnidirectional image at least includes one region which meets the special mapping relationship. The present invention can enable the regions in the decoded omnidirectional image to be distributed more uniformly than the sphere, thereby improving representation efficiency, and reducing conversion distortion. While designing the omnidirectional image processing method, the present invention also designs the corresponding device.