–In contrast with the conventional trinocular planar image stereo in which the third camera is usually used to reduce the ambiguity on matching, every spherical camera of trinocular spherical stereo plays a role which cannot be replaced by the other two since binocular spherical stereo cannot recover the distance information of scene points whose projection is on the baseline in spherical images. Using three spherical cameras which are not aligned with a straight line the distance cue of points near the baseline of one pair of spherical images can be recovered from the other; thus, we can acquire the whole surrounding structure of environment by trinocular spherical stereo approach. In this paper we give the definition, algorithm and experimental results of trinocular spherical stereo.