In catadioptric omnidirectional imaging systems, defocus blur is mainly caused by lens aperture and mirror curvature. The problem of image definition caused by defocus blur becomes more severe when high resolution sensors and large apertures are applied. One design of catadioptric omnidirectional imaging system for defocus deblurring, which is based on coded aperture, is proposed. The defocus blur of catadioptric omnidirectional imaging is analyzed in theory, and a method of obtaining optimal focused plane is proposed. With strategies of annuluses division and stitching of omnidirectional images, a deconvolution algorithm based on image sparse prior is used for the defocus blur omnidirectional image restoration to obtain all sharp omnidirectional images. The method is effective for catadioptric omnidirectional image defocus deblurring, which has an important meaning in improving catadioptric omnidirectional imaging quality and promoting applications in related fields.