Two rhombohedral corundum- type In2O3 (rh-In2O3) nanostructures were successfully prepared through solvothermal synthesis of InOOH precursors combined with post-annealing treatment. One is a unique and monodisperse urchin- like rh-In2O3 with three dimensional structures; another is a small size rod-like rh-In2O3 with two dimensional nanostructures. The morphological difference of the two InOOH precursors was mainly controlled by sodium dodecyl sulfonate (SDS) which acted as a soft template during the synthesis. The measurements of X-ray photoelectron spectroscopy, nitrogen adsorption and optical absorption indicated that the both obtained rh-In2O3 nanostructures are mesoporous materials which may possess oxygen vacancies and narrower band gaps. The photocatalytic activities of as-prepared urchin-like and rod-like rh-In2O3 were investigated by degrading oxytetracycline (OTC) under ultraviolet light irradiation. Compared with a commercial In2O3, the two above rh-In2O3 nanostructures exhibited an absolute superiority on photo-degrading OTC. Furthermore, the probable photocatalytic reaction mechanism was discussed and proposed according to radical trapping experiment and the detection of degradation intermediates.